OKLAHOMA CITY -- Paul George gave Russell Westbrook a pretty nice birthday gift -- even if two of the Oklahoma City Thunder's starters missed out.

After a 42-point outburst two days earlier, George scored 37 points to lead the Thunder, who were without starters Steven Adams and Carmelo Anthony, to a 112-99 victory over the Dallas Mavericks on Sunday night.

There was no cake for Westbrook, just a second straight look at what the Thunder might look like when operating a full strength.

"It's a learning process for myself," Westbrook said. "My job is to find spots where those guys are the most comfortable and get them the basketball there."

Westbrook finished with 27 points but missed out on a triple-double for the sixth straight game. Westbrook set an NBA record with 42 triple-doubles last season. His six-game drought matches his longest from last season.

Anthony was a late scratch from the game with back soreness, and Adams missed his second consecutive game with a right calf contusion.

It didn't seem to slow down the Thunder (6-7), who surged to a 39-point third quarter to set a season best.

"More shots!" George laughed when recalling the change with Anthony out of the lineup. "Nah, I'm just playing! We've got to be ready for anything. ... We've got to be that team.

"We're fortunate to have two other guys who can take the load, but it's even better when we've got young guys who can step up and help the team. As much as we wanted Melo out there, especially with how we've been playing, and to continue on with that chemistry, but at this point, it's great, especially early on, to be able to plug young guys in. They've just fit right in."

Midway through the third quarter, Westbrook hit 3-pointer to push the Oklahoma City lead to 13 points, forcing a Dallas timeout. He then motioned to the crowd for more noise.

The Thunder, who have won seven of its last eight regular-season games against the Mavericks, led by 16 points to start the fourth quarter and by as many as 21 in the fourth.

"Giving up 39 in the third, that was the game," said Mavericks coach Rick Carlisle, who remained tied for 18th all-time in coaching wins. "We outscored them in the other three quarters combined. By a point, but we did. You have to put four quarters together in this league."

Harrison Barnes led Dallas with 22 points, Yogi Ferrell added 18 and Dennis Smith Jr. scored 15 points for the Mavericks (2-12), who have lost eight of their last nine games.

The Mavericks turned over the ball 20 times, leading to 28 points for the Thunder.

Dwight Powell scored 11 points off the bench.

"We knew who the usual suspects were," Barnes said. "We knew (George) had a game going, and we knew Russell was going to be aggressive. We just have to do a better job. ... Any time you allow 39 points in a quarter, it's going to be hard to win. That's what happened."

Westbrook, who added six rebounds and five assists, finished 12 of 13 from the free-throw line -- a season high in attempts and makes -- to lead the Thunder's assault on the charity stripe. Oklahoma City went 25 of 33 from the line and has 73 attempts in the last two games.

George added eight rebounds and five assists and shot 54.5 percent from the field.

Dallas returns to action Tuesday against San Antonio after losing the second half of a back-to-back for the fourth straight time to start the season. Oklahoma City closes out a three-game homestand against Chicago on Wednesday.

NOTES: Thunder F Jerami Grant started in place of Carmelo Anthony, scoring 10 points in his fifth career start. ... Dallas F Harrison Barnes, the Mavericks' leading scorer this season, appeared in his 400th career game. .... Mavericks F Dirk Nowitzki was issued a flagrant foul midway through the second quarter and received a technical after arguing the call. ... Thunder F Patrick Patterson scored seven points in the first half to set a season high. He came into the game averaging just 2.3 points per game and had never scored more than six. ... Thunder G Josh Huestis scored a career-high nine points, six in the second quarter. ... Mavs reserve G Devin Harris missed Sunday's game with bruised ribs.