OKLAHOMA CITY (AP) — Marcus Smart scored a career-high 26 points to help the Boston Celtics beat the Oklahoma City Thunder 100-85 on Sunday night.

Isaiah Thomas scored 20 points, Avery Bradley had 14 and Jared Sullinger added eight points and 15 rebounds to help the Celtics win their third in four games. Boston shot 48 percent and outrebounded the Thunder 47-34.

Smart, who played college ball at nearby Oklahoma State, also guarded Russell Westbrook effectively. He was part of a collective effort that held the reigning scoring champion to 5-for-20 shooting. Westbrook still scored 27 points and carried a larger load with Kevin Durant out with a hamstring injury.

Serge Ibaka scored 16 points, and the Thunder had a season-low point total and their worst shooting performance.

Westbrook had posted triple-doubles in his previous two games but finished this one with just five assists and four rebounds.

Oklahoma City’s three-game win streak was snapped.

The Thunder led at halftime 52-45 behind 17 points from Westbrook. They pushed the lead to 11 early in the third quarter, but the Celtics rallied and trimmed their deficit to 74-72 by the end of the third quarter.

Boston finally took the lead early in the fourth quarter on a 3-pointer by Thomas. Back-to-back 3s by Thomas and Avery Bradley pushed Boston’s lead to nine, and a layup by Thomas bumped it to double digits for the first time. The Celtics never lost control from there.