BOSTON -- Isaiah Thomas had a fan in the front row Wednesday night, with boxing great Floyd Mayweather cheering him on.

Boston's little big man almost needed the boxer after the game.

In the moments after Thomas scored 20 of his 38 points in the fourth quarter to lead the undermanned Celtics to a 117-108 victory over the Washington Wizards, Thomas found himself in the middle of a disagreement involving the teams as they left the court.

As it turned out, Mayweather, who left with Thomas' jersey, wasn't needed.

"I just tell guys, 'Keep it hoop,'" Thomas said. "Nobody's built like that (a boxer), but the guy that was in that front row, Floyd Mayweather, so just keep it hoop and then move onto the next one."

Bad blood between the teams started back in November, when Washington guard John Wall was ejected for a flagrant-2 foul against Boston's Marcus Smart. Smart pulled Bradley Beal down during Wednesday's game and later committed a hard foul. Then, after Thomas' latest fourth-quarter heroics, there was suddenly a crowd in front of the Washington bench, apparently with Smart jawing at Beal.

Boston's Jae Crowder wound up pointing a finger in Wall's face, and Wall, who just endured a 4-for-21 shooting night, slapped at Crowder's face and missed. He then appeared to throw a jab over a shoulder and missed that, too, as his poor aim continued.

"Just some altercation," said Wall, who played with an injured hand that had to be X-rayed. "We knew there was going to be some trash talking. We knew it was going to be a physical game. That's all it was. Just a little trash talking and a physical game."

Smart was led away by team personnel, and there were five uniformed police officers in the hallway between the two locker rooms -- just in case.

Thomas started his surge with eight consecutive points in 47 seconds. He extended that to 14 in a 2:14 span, and his 20 for the quarter gave him the league lead in fourth-quarter scoring over Russell Westbrook. He was 7 of 12 from the floor in the quarter, 3 of 5 from 3-point range. One was a bomb that led to a high-five from Mayweather, another produced a Michael Jordan-style shrug.

"He's been playing as impressive as I've seen someone play," teammate Al Horford said of Thomas.

In addition to propelling his team to its fifth win in six games, Thomas got a measure of revenge against Wall.

Thomas thought he should have been the Eastern Conference player of the month for December, but the award went to Wall. On Wednesday, Thomas won the battle, adding six rebounds and five assists. Wall scored a season-low nine points to go along with 10 assists and seven rebounds.

"I'm dealing with my right pinky, left wrist is swollen," Wall said. "I knew it was painful before the game. It was a big game for us. I just tried to come out and play through it."

There were five technical fouls in the game, the fifth called on Beal after he reacted to being taken down by Smart.

The Celtics (24-15) exploded for a 13-0 run over 2:47 late to put the game away.

Boston went 17 of 41 from 3-point range, hitting at least 17 treys for the fifth time in six games after doing so just three times in franchise history.

The Celtics, who improved to 6-3 on the back end of back-to-backs (Washington is 1-7), were missing starters Avery Bradley (Achilles) and Amir Johnson (ankle), along with three others, including rookie Jaylen Brown (ankle).

Crowder scored 20 points, finishing 4 of 6 from 3-point range, and Horford had 16 points and nine rebounds, helping overcome 35 points by Beal, who got into foul trouble and was cold down the stretch after returning with four fouls.

Washington's Otto Porter Jr. contributed 20 points, six rebounds and five assists, while Markieff Morris posted 14 points, nine rebounds and four assists. Marcin Gortat added 10 points and nine boards.

Boston's injuries led to Jordan Mickey making his first NBA start. He logged 14 minutes, all in the first three quarters, finishing with four points and two rebounds.

It was Thomas' 23rd straight 20-point game. He failed to score 20 in only one game this season, when he had 18. He said Mayweather told him, "You playing like me out there. "

NOTES: Boston's absent players included G/F James Young (ankle) and C Tyler Zeller (illness). ... Celtics coach Brad Stevens told F Jordan Mickey he was starting with a morning text. As Mickey spoke to the media pregame, G Gerald Green shouted, "Don't be Hollywood now, boy." ... Rookie G Tomas Satoransky didn't make the trip with the Wizards because of illness, missing his second straight game. ... Washington opens a three-game homestand against the Philadelphia 76ers on Saturday night. The Celtics visit the Hawks on Friday -- Al Horford's return to Atlanta -- before playing five of the next six at home. Boston F Amir Johnson (ankle) is doubtful for Friday.