In the chaos of the final moments, Marcus Smart saved the Celtics

Marcus Smart pushes past Oklahoma City’s Shai Gilgeous-Alexander in the second half of Sunday’s game.Kyle Phillips/FR171277 AP via AP

OKLAHOMA CITY — After the Celtics escaped with a 112-111 win over the Thunder on Sunday, point guard Kemba Walker was asked what it is like to play with someone like Marcus Smart, who so often makes chaos look comfortable.

“Man,” Walker said. “Where do I start?”

In this case, it is best to start at the end. The Celtics had a 9-point lead with just 1 minute, 10 seconds left, and then most of it disappeared. Suddenly, Thunder guard Shai Gilgeous-Alexander was rushing upcourt in the final seconds with a chance to hit a 3-pointer that would have sent the game to overtime.

Smart stepped forward, stayed calm, and held his ground. And as Gilgeous-Alexander dribbled near the left arc, Smart reached in and poked the ball away before grabbing it, sealing his team’s seventh consecutive win.

“That was an unbelievable steal by Marcus,” Celtics coach Brad Stevens said.

Smart understood the significance of the sequence, but when reciting it afterward he mostly shrugged. He is on this team for moments like that.

“I just felt like I needed to make a play,” he said, “and it was right there for me to make.”

The 47-plus minutes that preceded Smart’s steal had importance, too. It was a rare instance in which the Celtics were operating with all of their top players on the court together. And it offered a reminder, on the road against a very good Western Conference playoff team, of what it looks like when Walker, Jayson Tatum, Jaylen Brown, and Gordon Hayward are all humming at once.

Walked finished with 27 points, Tatum had 26 points and 11 rebounds, Brown had 17 points and Hayward added 13 points and 10 rebounds. Hayward led the team in scoring in the first quarter, Tatum held the honor in the third and Walker took care of the fourth.

“It’s all about who’s got the hot hand at the time,” Walker said. “We have so much talent on the perimeter, it could be anybody’s night. Tonight was pretty well spread out. Guys just made huge plays at different times.”

It’s unclear how long the Celtics will have their full core, however. Brown, who has missed five games because of ankle injuries over the past month, agitated his right ankle sprain when he landed awkwardly midway through the third period.

He returned to the game but said he later rolled his left ankle while overcompensating for the previous injury. He said he hoped to play against the Rockets on Tuesday, but acknowledged that with just two games left before the All-Star break, some extended rest might be best. Before he limped out of the locker room, he joked that he did not know which leg he should be limping on.

“It’s been a frustrating few weeks,” Brown said, adding later: “My team needs me out there, and they need me healthy at the same time. We’ll see how it goes.”

Jaylen Brown defends Oklahoma City’s Chris Paul in the first half of Sunday’s game.Kyle Phillips/FR171277 AP via AP

Earlier in the day backup center Robert Williams, who has been sidelined for two months because of a bone edema in his left hip, completed his first full workout since he was hurt. He bounded into the locker room afterward and screamed with joy, saying that it felt wonderful to be able to run and jump without any limitations. Williams is expected to return to full practices after the All-Star break.

Even with Williams out, though, Boston’s frontcourt has held up well. On Sunday, with the Thunder’s defense swarming toward the Celtics’ dangerous wings, Daniel Theis remained a valuable safety valve. He finished with 13 points, 11 rebounds, and 5 assists.

“He covers up a lot for us,” Stevens said. “He did a really good job and he plays stronger than his weight would indicate.”

The Celtics were outrebounded, 27-22, in the first half and came up with just three offensive rebounds. In the second, they held a 31-17 edge that included 11 offensive rebounds. They also drilled 7 of 13 second-half 3-pointers, helping them wipe away an early 10-point third-quarter deficit.

Jayson Tatum goes up for a shot over Oklahoma City’s Steven Adams in the second half of Sunday’s game.Kyle Phillips/FR171277 AP via AP

Tatum was masterful in that period, both slicing through waves of defenders for layups and spotting up for deep 3-pointers. He was often matched up against his former mentor, the 6-foot All-Star Chris Paul, and he looked to use his size advantage when he could.

Danilo Gallinari caused fits for the Celtics by pouring in 24 points. But this is not football, so he had to try to guard people, too. For long stretches of the second half, the Celtics looked to attack the slow-footed big man when he switched onto their quick wings after screens. It usually ended well for the Celtics.

“We just wanted to use our speed against him,” Walker said. “Just made some huge plays. That was the matchup we wanted to go to.”

Walked burned Gallinari for back-to-back 3-pointers that helped Boston to a seemingly comfortable 110-101 fourth-quarter lead with just 1:15 left.

But the Thunder made a push, pulling within 110-106 on a Dennis Schroder 3-pointer with 46.2 seconds remaining. Walker made one of two free throws before Paul raced the other way for a layup that made it 111-108 with 16.4 seconds left. But Smart ensured that there was nothing else to worry about.