How the Celtics’ small lineup shut the Warriors down in Game 1

Led by Al Horford’s two-way versatility, the Celtics blitzed Golden State in the fourth quarter to steal Game 1. Plus, more observations from the opener of the NBA Finals.

The NBA Finals offered hope of change from the lopsided contests that have dominated the playoffs, and Game 1 delivered with a crisp, tightly contested game that set the tone for what should be a competitive series. The final margin — 120-108 in Boston’s favor — might suggest a fairly significant gap between the Celtics and Warriors, but the vast majority of the game featured two heavyweights trading blows, finding counters and grinding out possessions in a close affair.

Golden State’s unique motion offense almost always catches opponents off-guard in the first games of playoff series, but after weathering a third-quarter avalanche from Golden State, the Celtics finally pulled away in the fourth, using a 17-0 run to sprint down the stretch and secure a crucial, well-earned road win.

Aberrational shooting played a big role in Boston’s 40-point fourth quarter and 130.4 offensive rating for the game, but so did its superior execution and ball movement over the final eight minutes. The Celtics’ closing lineup of Marcus Smart, Derrick White, Jaylen Brown, Jayson Tatum and Al Horford outscored the Warriors by 13 points in over six minutes of action in Game 1, and all five players were essential to Boston’s late turnaround.

Brown helped ignite the fire that ultimately scorched Golden State in the fourth, scoring or assisting on the first 14 Celtic points of the quarter and prompting Steve Kerr to bring Steph Curry back in the game earlier than usual. Smart and White doggedly chased Curry around the floor, while Tatum consistently made the right plays on both ends despite a poor shooting night. But the most important Celtic in Game 1 might have been Horford, whose defensive mobility, 3-point shooting and connective playmaking changed what was possible for both offenses in the final quarter.

In his first-ever Finals game, on the eve of his 36th birthday, Horford had 26 points, six rebounds and three assists on 9-of-12 shooting (including a career-best 6-of-8 from deep), and was both a catalyst and a beneficiary of the Celtics’ sharp ball movement. It wasn’t just Horford’s statistical production that changed the tenor of the game late, but the way he opened up Boston’s offense while quelling the Warriors’ attack. Golden State used Curry in ball screens much more often than they had in previous rounds of the playoffs, which is a testament to how well the Celtics defended the Warriors’ preferred approach of passing, cutting and moving without the ball.

But leaning into the two-man game allowed the Warriors to target Robert Williams when he was on the floor with Curry, taking advantage of his limited mobility on the perimeter by using his man to screen for Curry. That not only mitigated Williams’ massive impact as a rim-protector but forced the Celtics to either concede open shots to Curry or scramble to take him away. In the first and third quarters, that helped Curry get going from deep before the Celtics began pre-switching the pick-and-roll to keep Williams in the paint while Horford came up to defend the screen:

Going smaller with Grant Williams in place of Robert Williams helped quiet Curry in the second quarter, but with Horford off the floor in the second half, Boston went back to dropping and trapping against Curry. That let Golden State play four-on-three, put the Celtics into rotation and create open shots, and some of the Warriors’ only good offense in the fourth quarter came at Rob Williams’ expense in basic pick-and-rolls:

When Boston tried switching Williams onto Curry, the two-time MVP simply isolated and got to an easy mid-range jumper. Ime Udoka then countered by replacing Williams with the quicker and more skilled Derrick White, leaving Horford as Boston’s lone big man. Now, the Celtics could more effectively get into Curry’s airspace without putting two defenders on the ball while stretching the Warriors out on the other end.

“At times some of our bigger guys were getting caught too low, especially when Curry was getting going early, so we wanted to go with a smaller unit and get more aggressive on the ball,” Udoka said postgame. “We did some pre-switching to get the bigs out of the actions and took some time off the clock, and this is what we relied on all year — our one-on-one defense. And guys really clamped in a little bit better. More physicality, more awareness on their shooters taking up some space, and it seemed like it seemed to wear them down a little bit.”

By cleaning up its on- and off-ball switches, Boston forced Curry into more on-ball work, only without the advantage of fully tilting the defense away from his teammates. Instead of walking into open 3s or getting off the ball against double-teams, Curry now had to do more heavy lifting to get his shot off and scored just once after Horford checked back into the game with 6:34 remaining. Horford, meanwhile, splashed two 3s, hit a mid-range jumper and converted an and-one to ice the game over that time — all while anchoring a smothering defensive lineup.

Horford will always be miscast as a primary offensive creator or central defensive pillar (especially at this stage of his career), but his ability to fill any gap on either end of the floor makes him essential to a team as balanced and versatile as the Celtics. Subtle acts like playing a step higher on the floor against Curry, instantly spotting an open shooter with a kickout pass, popping to the perimeter out of ball screens and boxing out on every Warrior shot attempt all compound into a massive effect on the final score. In Game 1 that impact was fully evident, and it helped give Boston a critical early edge in the NBA Finals.

“It’s just going out there and playing basketball at the end of the day,” Horford said postgame. “That’s just what it is.”

More notes and observations from Game 1 of the NBA Finals

White probably won’t shoot as well over the rest of the series (though there is mounting evidence that becoming a father during the playoffs provides some sort of supernatural 3-point shooting boost), but his decisiveness on offense and unique combination of screen navigation and switchability on defense will keep him front and center in this series.

Boston did a fantastic job driving to pass in Game 1, particularly out of isolation. I worried coming into the series that the Celtics might get baited into playing one-on-one and forcing bad shots against Curry, Looney and Poole, but they did an excellent job in Game 1 of using matchup advantages to draw help and find teammates — especially Tatum. Boston had 33 assists on 43 made baskets in the game, including a career-high 13 dimes from Tatum to go with only two turnovers.

“It’s such a challenge for guys like him and top players in the league who are expected to score, to playmake, to defend, all those things, and Jayson does all those things,” Horford said. “His playmaking has gotten better steadily, and tonight it was just brilliant.”

Despite Tatum’s 3-for-17 shooting line, the Celtics had a 131 offensive rating in his 42 minutes — a reflection of his strong creation for others. Brown also played an excellent floor game, tallying five fourth-quarter assists and showing an unusually high level of discernment with the ball in his hands. Like Tatum, he sought out cracks in the Warrior defense not just to score, but to collapse the defense and make plays, which eventually allowed him to find scoring opportunities within the flow of the offense.

“Early in the game he got a little dribble-heavy at times, had some turnovers and some tough shots, and we showed that at halftime we don’t have to take any of those,” Udoka said. “They’re gonna collapse the paint, know where your outlets are at, let’s get our spacing correct, and they do have some favorable matchups for us that we can attack.”

Brown’s balance between downhill aggression and controlled probing was perhaps most evident on the play that effectively sealed the game, when Tatum drew two defenders on a high pick-and-roll and quickly found Smart on the roll. Smart instantly swung the ball to Brown, who then drove the baseline and shoveled a pass to Horford for an and-one:

Brown did have four turnovers, but if he and Tatum keep passing like they did in Game 1, the Celtics’ offense becomes much more dynamic and harder to stop.

The Warriors finished the game with a 115 offensive rating, but they must find ways to generate offense that don’t involve spamming Curry pick-and-rolls or relying on offensive rebounds. They took advantage of Boston’s sloppy off-ball and transition defense in the first quarter, but their best stuff in the second half came almost exclusively via second-chance 3s and ball screens for Curry. Poole and Klay Thompson combined for 24 points on 8-of-21 shooting, while Draymond Green shot an abysmal 2-for-12 from the field. Credit the Celtics for shutting off most of the handoffs, cuts and off-ball screens that make Golden State so deadly, but expect the Warriors to tweak their lineups and halfcourt tactics in Game 2 to juice their offense.

Let’s take a moment to appreciate the rugged greatness of Kevon Looney, who blocked three shots, dished out five assists and gathered six offensive rebounds to continue a superlative playoff run (a brief stretch against Memphis notwithstanding). Despite often resembling an old, beat-up truck that looks like it could break down at any moment, Looney seemingly always finds a way to deliver crucial plays on both ends of the floor that either keep or swing momentum in Golden State’s favor. He’s been an insatiable offensive rebounder and terrific all-around defender throughout the postseason, and does so much of the grunt work required to grease Golden State’s free-flowing offense. All of that said, Looney’s limitations as a shooter do impose minor offensive limitations, which might cause Kerr to play Green at center more often in Game 2, especially late.

Despite getting played off the floor late, Robert Williams’ defense at the rim was outstanding in Game 1. He had four blocked shots, and the Warriors struggled to generate much of anything in the paint with him on the floor. Golden State doesn’t attack the rim much off the dribble, but their ability to spread opponents out and move without the ball creates chances off of cuts and dropoff passes, so having a defender like Williams (even in his diminished state) who can erase those layups makes a big difference.

After not playing since April 24 against the Nuggets, Iguodala played 12 solid minutes in Game 1, and having him on the floor seemed to settle the Warriors’ offense. It might be asking too much of a 38-year-old coming off a neck injury to play more than 20 minutes per game, but the more the Warriors can get from Iguodala, the better.

Otto Porter Jr. also looked good coming off a foot injury, hitting four of his five 3-point attempts and playing his usual active defense. Gary Payton II was active but didn’t play, and there may not be much of a place for him in the series if Green, Iguodala and Looney are all fixtures in the rotation. Still, he might provide a different look in Game 2 coming off a home loss.

As well as the Celtics played on both ends in Game 1, they undoubtedly benefited from outlier shooting performances by their role players. Celtics not named Jaylen Brown or Jayson Tatum shot 18-of-28 from 3, and both Kerr and the Warrior players seemed to implicitly attribute much of Boston’s fourth-quarter run to shooting variance. Frankly, they’re probably right to believe the Celtics won’t shoot 51 percent from deep in every game of the series.

“My gut reaction, just what I just witnessed, was they came in and played a hell of a fourth quarter, and you’ve got to give them credit,” Kerr said. “It’s pretty much as simple as that.”

Better shooting from Tatum (and probably Brown) should balance out regression from lesser shooters, and the Warriors themselves shot a scorching 46 percent from distance. Maybe it all balances out. But Curry, Thompson and Porter catching fire from deep feels more sustainable than Horford, White and Smart doing the same, and the Celtics could have trouble scoring in this series when shots aren’t falling the way they did on Thursday. Both teams have reason to feel confident moving forward, and in many ways the series remains on level ground strategically. The difference is that Boston now has a one-game advantage, and it’s now the Warriors’ turn to respond.