"I thought a lot of guys did a great job of competing," Thunder coach Scott Brooks said. "We played tough tonight."
The Thunder held Washington scoreless in the final 2 1/2 minutes, handing the Wizards their third straight loss and fifth in six games.
Antawn Jamison had 29 points and 10 rebounds for the Wizards, who have been banged up all year and played without Caron Butler for the second straight game. Andray Blatche and Darius Songaila scored 14 points each.
Sefolosha, known more for his defense, made a reverse layup with 1:47 to play to give Oklahoma City an 84-83 lead and the Thunder didn't trail again. A jumper by Westbrook with 33.3 seconds remaining stretched the lead to three and Nenad Krstic added two free throws with 9.5 seconds left.
Krstic finished with 18 points, Sefolosha had 15 and Westbrook 12 with eight assists. Nick Collison added 12 points and 10 rebounds.
"With Jeff and Kevin (out), we all had to step up and play together," Westbrook said. "Everybody played great on the offensive and defensive end."
Sefolosha scored seven in a row, including a 3-pointer, to give the Thunder a 59-52 lead midway through the third quarter. Oklahoma City got a boost from Damien Wilkins later in the quarter when he made three baskets to stretch the lead to 67-58.
The Wizards cut the margin to five by the end of the period, then outscored Oklahoma City 14-4 in the first 5 minutes of the fourth quarter to take the lead. Washington led 83-82 after two free throws by Dominic McGuire with 2:32 remaining, then didn't score again.
"We didn't move around properly on the offensive end and it hurt us around the last two minutes of the game," Jamison said. "We didn't get any stops down the stretch. They had some of their studs out tonight and we thought if we brought the effort we would come out with a win."
Jamison had 17 points in the first half when the Wizards opened a seven-point advantage. Three straight baskets by Krstic and a shot by Westbrook brought the Thunder back before Jamison ended the run with a drive inside.
The Wizards consistently scored in close during the first half. They outscored the Thunder 30-24 on points in the paint and had a 14-2 edge in second-chance points. Songaila did a lot of that damage, scoring 10 first-half points.
Jamison had just one field goal in the third quarter when the Thunder went ahead by nine. Collison had six of his rebounds during the period.
Oklahoma City coach Scott Brooks again dipped deeper into his bench, with good results. Robert Swift, playing in his third straight game after missing 20 of the previous 21, contributed six points and three rebounds in 16 minutes. Wilkins also came off the bench and finished with eight points and seven rebounds.
Notes: Butler, averaging 20.3 points per game, missed his second straight game due to tightness in his left hamstring. ... Four purple heart winners received a standing ovation at halftime when they were honored as part of an evening-long salute to current and former members of the armed services. ... Washington had won five in a row against the Oklahoma City franchise.