Mason, averaging 8.6 points and 21 minutes a game, came off the bench to pump in five 3-pointers in the fourth quarter, leading the Wizards to a 104-99 victory over the Seattle Supersonics on Wednesday night.
The Wizards (37-34) remained a half-game ahead of Philadelphia for sixth place in the East. The Sixers beat Chicago 121-99.
"Roger Mason really bailed us out tonight," Washington coach Eddie Jordan said.
Mason matched his career high with six 3-pointers, and Caron Butler had 21 points. He's averaging 27.8 points in his last seven games against the Sonics.
Seattle (17-55), which beat Portland on Monday, has not won consecutive games since winning a season-high three in a row Jan. 29-Feb. 2.
Washington, still without Gilbert Arenas, recovering from offseason knee surgery, was playing the second of back-to-back games to begin this five-game West Coast trip. The Wizards lost listlessly to Portland on Tuesday, 102-82.
"That's been my role all year," Mason said. "When guys have been out, I've been able to step up. Tonight was no different. Whether it was back-to-back games or not, we had a 17-point deficit in the third quarter. We needed energy off the bench."
The Sonics grabbed the momentum over the final 2 minutes of the first half, scoring the final eight points, six by Durant. That carried over into the third quarter, as they opened with a 17-6 run for a 73-56 lead with 5:47 left.
Coming out of a timeout, Brendan Haywood's putback basket started a 10-0 run to begin the Wizards' comeback.
Mason hit a 25-footer to open the fourth quarter as the Wizards chipped away. Mason's 3 with 8:25 left gave the Wizards their first second-half lead, 84-83. By the time he hit his fourth 3-pointer, the Wizards had a 95-89 lead.
"Every team goes on a run, but he [Mason] was phenomenal," said Durant. "Once he got hot, they took off from there."
The young Sonics, with three solid quarters, were unable to find Mason through the screens down the stretch.
"We played a lot of good minutes to put ourselves in position to win the game," Sonics coach P.J. Carlesimo said. "They're a good team. They're not just going to go away.
"We couldn't guard Roger. We couldn't guard Caron. And we had trouble guarding Darius [Songaila]."
Reserve Songaila scored 10 points, eight in the final period.
Antawn Jamison, averaging a team-high 21.6 points, has struggled on back-to-back nights. He scored just nine points on 3-for-13 shooting Tuesday at Portland. He was better against the Sonics, hitting 6 of 17 attempts. Eight of his points came in the final period.
Wilkins hit a pair of quick baskets to open the second quarter and give the Sonics the energy they needed. By the 9:42 mark, his two free throws gave the Sonics their first lead, 33-31.
Collison had perhaps his best career half on the boards, collecting 15 rebounds. No other Sonic had more than four.
Carlesimo said before the game that "there is not one iota of doubt" who he believes is the NBA's Rookie of the Year: Durant. The league's overall No. 2 pick leads the Sonics and all rookies in scoring at 19.6 per game. ... This was the second of five straight games for the Wizards against Western Conference teams. They continue their road trip against Sacramento on Friday, the Pacific Division-leading Los Angeles Lakers on Sunday and Northwest Division-leading Utah on Monday.