BOSTON -- Boston Celtics guard Isaiah Thomas didn't know Floyd Mayweather was going to be at TD Garden for Wednesday's game against the Washington Wizards. But Thomas treated his good friend to a show for making the trip.

Thomas scored 20 of his game-high 38 points in the fourth quarter to help the Celtics rally for a 117-108 triumph at TD Garden. As part of his final-frame outburst, Thomas made a couple of deep 3-pointers right in front of Mayweather and even took time to dap him up after one of them -- knocking some of the bling straight off Mayweather's wrist with an emphatic slap.

Thomas and Mayweather are longtime friends, and Thomas jokes that the Celtics "usually win when he's in the building." Mayweather was shown on the Garden's JumboTron during one fourth-quarter timeout, and he playfully held up the Celtics' cap of a companion as the crowd roared.

Immediately after the final buzzer, Mayweather asked Thomas for his game-worn jersey and Thomas obliged, hoping for a gift in return.

"I wanted that jewelry," Thomas said of Mayweather's glitzy chains and wristwear. "I didn't want the jacket. That's too small for me. I wanted that jewelry."

Thomas made 7 of 12 shot attempts in the fourth quarter, including three 3-pointers. TD Garden serenaded him with now-familiar "MVP" chants as he attempted free throws with 72 seconds to play.

After hitting a pull-up 3-pointer in transition in a one-point game with about seven minutes to go, Thomas pointed at his wrist while walking back up the court, whipping the Garden into a lather by suggesting the fourth quarter is his time.

"They know what time it is," Thomas said. "Yeah, I thought about [that celebration]."

With his 20-point, fourth-quarter output, Thomas overtook Oklahoma City Thunder guard Russell Westbrook as the NBA's leading fourth-quarter scorer this season. Thomas is now averaging 9.8 points per game in the fourth quarter compared with Westbrook's 9.6. No other player is averaging more than 7.8 points per game in the fourth this season.

"Not to sound cocky, I just feel [these fourth-quarter outbursts are] normal," Thomas said. "Honestly, I work on all those shots that I shoot, and when I’m out there, I know the fourth quarter is the time for me to be more aggressive. My teammates look for me to be that, and I just go out there without a care in the world."

Thomas hinted he might have had some extra motivation after Washington's John Wall earned the Eastern Conference's Player of the Month honor in December -- even though Thomas averaged better than 30 points per game in the month.

Wall finished Wednesday's game with 9 points, 10 assists and 7 rebounds over 39 minutes.

"I'm aware of everything," Thomas said. "You can put it how you want to. I see everything."

So did it mean more to have a big night against Wall?

"Yeah, because he's a hell of a player. An All-Star-level player," Thomas said. "That's the franchise of that team, and we did a good job. Not just whoever guarded him, but as a team, collectively, we did a good job of making it tough for him. That's what we have to do to beat good teams like that."

Thomas later referenced a Bleacher Report article that ranked him 11th among all NBA point guards.

"Everything motivates me," Thomas said. "Did you see that Bleacher Report thing that came out? It keeps going. It keeps going, so I think them and everybody else.

"They always send it to me. It's always on Twitter. So somehow it gets back to me, and I just shake my head."

Thomas said he was hoping to catch up with Mayweather again after Wednesday's game. Asked if he thought Mayweather would fight MMA star Conor McGregor, Thomas said he thinks it's unlikely but offered a prediction.

"Probably not," Thomas said. "But if he does, he's going to win. I know that."