Toronto, ON (SportsNetwork.com) - Marcus Smart's follow-up layup lifted the Boston Celtics to a 117-116 overtime win over the Toronto Raptors on Saturday night.

DeMar DeRozan, who had been the man for Toronto in overtime up to that point, drove the lane and dished out to Lou Williams for a 3-pointer which gave Toronto a one-point edge with 4.9 seconds left.

Isaiah Thomas was hung up on his drive on Boston's final possession, but Smart was there on the block for the layup at the buzzer.

"It was for Isaiah. We told everybody to crash," Celtics coach Brad Stevens said of the final play. "Isaiah got to the rim and did his job."

The Celtics have moved a half-game ahead of Miami for the eighth and final playoff spot in the Eastern Conference.

Thomas led Boston with 25 points, Tyler Zeller had 20 points with nine rebounds and Evan Turner chipped in 18 points with 10 assists in the win.

DeRozan went for 38 points in the setback, while Williams recorded 27 points off the Toronto bench.

"I like our effort. That was a playoff atmosphere," said Raptors coach Dwane Casey. "That team is playing well right now. It was a playoff-style game. It was physical."

Williams opened the extra session with a 3-pointer before Boston scored the next four points to regain the lead. DeRozan then hit consecutive buckets to push Toronto ahead 111-108 with 1:41 left. Smart, who scored 15 points, fired in a corner 3-pointer with 32.9 seconds left that moved Boston back in front by one, 114-113.

Williams and Terrence Ross each missed a 3-point attempt on the other side, and Brandon Bass eventually came down with the rebound for the Celtics. Bass made 1-of-2 at the line with 18.2 ticks on the clock to make it a 115-113 lead.

Toronto used a 10-3 run early in the fourth to cut its deficit to 84-80. Later in the quarter, Jonas Valanciunas made a hook shot in the lane before Williams converted two free throws that helped the Raptors close within 96-94 with 3:14 remaining.

The Celtics responded, however, with Thomas and Bass each converting baskets to extend their lead to 100-94. The Raptors countered that little flurry with a 6-0 run that tied the game at 100-100 with 53.3 seconds left in regulation

Turner and DeRozan went toe-to-toe in the final minute, as each made two baskets to keep the game tied. Thomas' 3-pointer at the buzzer was well off the mark and the game went to overtime.

"(The Raptors) made huge shots," Stevens added. "Those guys made big-time plays. Both teams did."

The Celtics opened the third quarter on a 15-2 over the first five-plus minutes. Zeller supplied eight points during the flurry, and he capped it with a pair of free throws for a 62-49 lead. Williams did all he could to keep the Raptors in the contest, scoring eight straight at one point, but Boston still managed to take an 81-70 lead into the fourth.

The Raptors went into the second quarter with a 24-15 lead. Boston got back into the game early in the second, as Turner netted six points during a 17-2 Boston surge that helped it regain the lead at 34-31. The game remained close the rest of the half with the both teams knotted at 47-47 at halftime.

Game Notes

Boston has won four straight on the road ... Toronto has lost two straight since a three-game winning streak ... The Celtics scored 25 points off 16 turnovers ... There were 14 lead changes and 11 ties.