MIAMI -- From blood on Boston Celtics center Kelly Olynyk's elbow to teammate Marcus Smart's blood boiling after being fouled intentionally and perhaps too physically, the evidence of a battle was there to be found.

But sometimes when you are in a battle, it's good to have the smallest guy on the court on your side.

That's what Boston had on Monday night as 5-9 point guard Isaiah Thomas scored 25 points and added eight assists to lead the Celtics to a 112-104 victory over the short-handed Miami Heat at AmericanAirlines Arena.

Thomas was held to 7-of-23 from the floor but made 9-of-9 from the foul line. That helped Boston overcome stellar performances by Heat center Hassan Whiteside (25 points, 17 rebounds) and point guard Goran Dragic (27 points, 17 assists).

Heat coach Erik Spoelstra called Thomas "relentless".

"He's a whirling top," Spoelstra said. "He's not going to let you off the hook for even one possession. He's always going to probe, to attack, to see if the defense is weak on any possession.

"Everyone talks about him being small. But he lives in the paint. He knows how to draw fouls and finish over bigs."

The Celtics (10-7) have won four straight in their series against the Heat (5-12), and all four of those wins occurred since Thomas arrived last season.

Boston has also won at least one game in Miami in 10 of the past 11 years.

The Celtics were without center and four-time All-Star Al Horford, whose wife was having their second child. But the Celtics responded, getting six scorers in double figures, including Olynyk (14 points) and Smart (12 points) off the bench.

Late in the fourth quarter, Smart picked up three quick fouls -- a flagrant, a personal and a technical -- as he and Dragic exchanged shoves.

"A little bit, especially if the refs don't call (fouls)," Olynyk said when asked if the game got nasty at the end. "(Miami) is intentionally fouling, and (the referees) are not calling it -- that's annoying."

Whiteside, who woke up on Monday with a sore left knee, turned out to be fine -- and then some. The same can be said of Dragic, who returned after missing two games due to a sore left elbow.

"Those two guys are a handful," Celtics coach Brad Stevens said, "and they proved that tonight."

The Heat also got a boost from reserve shooting guard Wayne Ellington, who had yet to play this season due to a deep bruise on his right thigh. He scored nine points in his Heat debut.

But even with Whiteside, Dragic and Ellington in the lineup, Miami was missing three of its five leading scorers, all out with injuries -- Justise Winslow, Tyler Johnson and Dion Waiters.

Already this season, Miami has nine players who have combined to miss 62 games.

Given that, it was no wonder the Heat trailed virtually the entire game. Still, it's likely few would have predicted it would have been so awful for Miami in the second quarter (just 12 points).

But that's how it went as Boston led 48-31 at the half. Miami shot 0-for-12 on 3-pointers and 1-for-19 outside the paint in the first 24 minutes.

Surprisingly, Miami followed its lowest scoring half of the season with its highest scoring quarter.

The Heat scored 42 points in the third quarter and cut Boston's lead to 83-73. With just 0.9 seconds left in the third, Miami threw a full-court pass to Ellington, who made an off-balance jumper at the buzzer.

But Miami never got closer than nine points in the fourth quarter, wasting the great efforts from Dragic and Whiteside.

"Give me just 10 points, and we win the game, and I'd take that immediately," Dragic said when asked about his big numbers. "I've already proven in this league that I can score. That doesn't mean anything to me.

"There are too many times in games where we are not focused."

NOTES: Heat SGs Dion Waiters (groin) and Tyler Johnson (dental surgery) missed their first games of the season. ... Heat SF Justise Winslow (wrist) missed his eighth straight game. With Waiters, Johnson and Winslow out, Miami was missing three of its top five scorers. ... The Celtics are 5-5 without C Al Horford this season. Celtics C Tyler Zeller started in place of Horford, who missed nine games earlier this season due to a concussion. ... Miami C Hassan Whiteside entered Monday leading the NBA in rebounding (14.9) and ranking second in blocks (2.5). ... Celtics G Isaiah Thomas entered Monday ranked ninth in the NBA in scoring (26.1). ... Up next, Miami will start a three-game trip at the Denver Nuggets on Wednesday. ... Boston returns home to face the Detroit Pistons on Wednesday.