DENVER — With 10 minutes left in the fourth quarter of the Celtics’ game against the Nuggets on Sunday, Evan Turner poked the ball away from Denver’s Jusuf Nurkic, and suddenly there was possibility. Marcus Smart, as is his usual way, dived to the floor and slapped the ball far downcourt with his left hand.

“The least I could do was try to run the play out and make something happen,’’ Turner said.

And that is what he did, sprinting toward the basket. Turner knew he could not catch up in time for a layup, but he’d briefly seen Avery Bradley running in that direction, too. So just before reaching the baseline, Turner scooped a pass backward, and Bradley caught it in stride and converted an easy dunk.

While this play was transpiring, while the Celtics were diving and sprinting and hustling, several Nuggets were simply walking upcourt, either resigned or simply worn out by their opponent.

After the Celtics came out of the All-Star break with a listless loss to the Jazz on Friday, this game provided a return to the hustling, havoc-filled style that has worked so well and made them so endearing, as they surged to a 121-101 win.

“Those are plays that help you win,’’ Celtics coach Brad Stevens said of the wild fourth-quarter sequence. “You feel like you’re going to win the game, or at least you’ve given yourself a good chance when you make plays like that.’’

Stevens was frustrated with his team’s effort in its 18-point loss to Utah in which it committed 31 fouls. The Celtics were not fully engaged and Stevens said they were not a presence defensively, either.

In this game, though, it was clear that issue had not lingered. The Celtics forced 24 turnovers and Stevens said that for most of the game, his team was as focused defensively as it has been in some time.

“We were locked in to the fullest,’’ Smart said. “We had an upset on the defensive end against the Jazz a couple nights ago, and it left a bitter taste in our mouth. We just wanted to come out here and redeem ourselves.’’

The offense’s flow, of course, has not been an issue. And it wasn’t in this game, either.

The forced turnovers allowed the Celtics to get out in transition, where they are most comfortable, to find plenty of easy baskets. Boston scored 60 points in the paint, and given its lack of a major interior presence, a statistic such as that indicates dunks and layups.

The Celtics scored at least 121 points for the third time this month. Previously, they had reached the 121-point mark just three times between February 2011 and January 2016.

“Everybody’s contributing,’’ Smart said. “We’re trying to move the ball more and everybody’s touching it, and we’re trying to go quickly.’’

The Celtics average a league-high 89.5 shots per game, and against Denver they attempted 97. Isaiah Thomas led Boston with 22 points and 12 assists, Turner had 17 points and nine rebounds, and Jared Sullinger added 16 points and 11 rebounds.

Nikola Jokic paced the Nuggets with 23 points and 13 rebounds, but coach Mike Malone was understandably in no mood to look at the bright side afterward.

“It was a lot more than a lack of energy,’’ Malone said. “It was a lack of fight, a lack of togetherness . . . We quit on a number of plays tonight, and I thought we played pretty selfishly.’’

With 3:11 left in the opening quarter, Smart drained a 3-pointer to cap a 23-5 run that gave the Celtics a 27-12 lead. That advantage continued to swell. The Nuggets were sloppy on offense and lazy on defense, as the Celtics grabbed several offensive rebounds after the ball had hit the floor.

Thomas had no trouble probing and finding space in the paint before kicking passes to open shooters. With 5:44 left in the second quarter he found Sullinger, whose jumper gave Boston its largest lead, 51-25.

D.J. Augustin, who was acquired from the Thunder just before Thursday’s trade deadline, sparked a 10-0 Denver run to keep his team within reach, and the Celtics went to halftime with a 64-49 edge.

With 8:51 left in the third quarter, a 3-pointer by Jokic pulled the Nuggets within 67-62. But the Celtics responded with a 9-2 burst highlighted by Smart’s steal that led to a Jae Crowder dunk, making it 76-64. Boston’s lead did not dip below 10 points after that.

“Everybody needs wake-up calls,’’ Sullinger said. “Even the best teams sometimes need wake-up calls. We understood what we had done the last couple of games, and we stepped it up on the defensive end.’’

Adam Himmelsbach can be reached at adam.himmelsbach@ globe.com. Follow him on Twitter @adamhimmelsbach.