The Raptors were outplayed by the Boston Celtics, 95-87.
Late in the 4th quarter, forward Jorge Garbajosa suffered a serious injury to his left ankle.
Garbajosa was taken to hospital for evaluation.
The extent of the injury will be announced later today.
The Raptors face the Miami Heat on Wednesday.
The Maple Leafs host the Carolina Hurricanes tonight.
Tonight's match is crucial as Toronto is two points from the 8th and final playoff spot, which is held by the 'Canes, the New York Islanders and the Montreal Canadiens, who are all tied with 84 points.
Puck drops at 7:30pm at the Air Canada Centre.
The Blue Jays tied, 2-2, with the Pittsburgh Pirates.
Pitcher Josh Towers gave another solid performance, allowing only one unearned run in six innings.
He also struck out five and walked one.
The Jays host the Tampa Bay Devil Rays this afternoon in Dunedin.
Scoreboard
OHL Playoffs
Ottawa 4 Belleville 3 (Ottawa leads 1-0)
OPJHL Playoffs
Aurora 3 Hamilton 4 (Series tied 1-1)
- ER