OKLAHOMA CITY — Marcus Smart scored a career-high 26 points to lead the Boston Celtics to a 100-85 victory over the Oklahoma City Thunder Sunday night at the Chesapeake Energy Arena.

Taking on the challenge of guarding Thunder guard Russell Westbrook, Smart was still able to shoot 9 of 14 from the field and haul in eight rebounds. Guard Isaiah Thomas scored 19 points and handed out eight assists as the Celtics improved to 5-4.

With guard Avery Bradley coming off the bench, the Celtics reserves torched Oklahoma City in the fourth quarter. They built an 11-point advantage and had control of the game midway through the quarter.

Oklahoma City brought its starters back in, but they lacked the energy to contend with the scrappy Boston squad. They got beat to loose balls, rebounds and were just out-hustled.

The Thunder never got closer than 12 points the rest of the way.

Westbrook had a game-high 27 points on 5 of 20 shooting. He shot 2 of 10 from behind the arc but was 15 of 17 from the free-throw line.

Center Steven Adams was the only other Thunder player in double figures with 16 points and 10 rebounds.

The Thunder dropped to 6-4 overall and 1-1 without forward Kevin Durant.

Back in the state where he played his college ball, Smart started the night like he was still playing for Oklahoma State. He shot 4 of 6 in the first quarter to knock in nine quick points. He would have hit double digits if he hadn’t missed three free throws.

But while Smart was attacking the basket, Westbrook was doing his damage from the perimeter. He attempted five 3-pointers in the first eight minutes of the game. He had been averaging only five 3-pointers a game on the season.

Oklahoma City was able to build a 10-point lead with less than a minute left in the first half. But the Celtics cut the lead down to 52-45 at halftime

The Celtics stormed all the way back in the third quarter to tie the game at 72-72. Smart continued his rampage and seemed to score at will. But it was forward Jae Crowder’s energy and defense that allowed the Celtics to storm back and only trail by two heading into the fourth quarter.

NOTES: After missing two straight games with a calf strain, Boston G Avery Bradley was back in the Celtics’ lineup Sunday. … Boston coach Brad Stevens was asked if his success has re-opened the college-to-NBA coaching transition: “We define ‘success’ differently,” Stevens said. … Thunder F Kevin Durant on his strained hamstring: “Feel a lot better. Feels way better, actually. You can re-injure (hamstrings) pretty easily if you try and play through it, or as we say now, ‘Be tough.’ I call that being dumb.”

Jazz 97, Hawks 96

Forward Derrick Favors returned to his hometown to score 23 points and grab eight rebounds, leading the visiting Utah Jazz to a 97-96 win over the Atlanta Hawks on Sunday at Philips Arena.

Favors, who grew up in Atlanta and played one season at Georgia Tech before turning professional, shot 11-for-20 from the field. His bucket gave the Jazz a five-point lead at 93-88, a margin from which the Hawks could not recover.

Favors also made an 18-footer as the shot clock was running out with 38 seconds left to extend Utah’s lead to four points. He scored 17 points in the second half.

Atlanta had one last chance to win the game. Center Al Horford made a 3-pointer with 33 seconds left to cut the lead to one, and the Hawks had the ball after Favors missed a jumper with 12 seconds left.

Forward Paul Millsap had an open look at the basket as time expired, but his 16-footer bounced off the rim and into the arms of Favors.

The win improved Utah’s record to 5-5 overall, 4-4 on the road. The Hawks dropped to 8-4 overall, 4-3 at home.

Utah guard Rodney Hood scored a season-high 20 points. Guard Alec Burks came off the bench to score 18 points and grab six rebounds. Center Rudy Gobert had 11 points and 11 rebounds, and guard Trey Burks contributed 10 points and five assists.

Millsap led Atlanta with 28 points, converting 10 of 18 from the floor, and he grabbed six rebounds. Center Al Horford and forward Kent Bazemore each had 16 points, and guards Dennis Schroder and Kyle Korver each scored 11.

Atlanta enjoyed a 79-74 lead with 10:08 left in the game before Utah began its fourth-quarter spurt. Burke hit a layup, and Hood drained a 3-pointer with 8:49 to tying the game 79-79.

The Jazz led 91-86 after forward Gordon Hayward made a 15-footer with 4:03 left. Atlanta trimmed the lead to two points when Millsap converted on a pass from Schroder, but Millsap also had a turnover and missed everything on a 3-point shot with 59 seconds left.