The Heat will be out to end the new-look Raptors' five-game win streak Sunday night at home.
LeBron James combined for 62 points on 62.2 percent shooting in road wins over Toronto (16-15) two months ago.
The Raptors are a different team now as winners of nine of 11 since Dec. 13 - the date when the majority of the players acquired from Sacramento in the Rudy Gay deal made their club debuts.
"We've been noticing," Miami coach Erik Spoelstra said. "They've been playing very good basketball. We mentioned that about the Eastern Conference. It is way too premature to figure out where teams are. There are teams that have higher ceilings, and they're one of them."
Toronto used to employ Gay primarily to defend James. With the swingman gone, coach Dwane Casey named more than half of his roster when asked who he would use Sunday, and even made a reference to a position that doesn't exist in a reference to James.
"They've got a power forward that's really a point guard, two-guard, three-guard all in one so you've got to do some special things to try to contain him," Casey said.
Miami (25-8) could be without starting forward Shane Battier, who sat out Saturday's 110-94 victory at Orlando to rest a sore quadriceps. Rashard Lewis replaced him in his first start since Nov. 27, and scored a season-high 18.
"We're a veteran team and I'm used to it after playing last year. You just have to be mentally ready to go when your name is called upon," Lewis said. "With the type of team we have you might play 20 minutes and you might play 5 minutes. You've just got to be ready."
Bosh, who made all nine shots from the field Saturday, is 8-0 in the games he has played against his former team. He missed the season's first meeting and scored four points for his worst output against Toronto in a 90-83 victory Nov. 29.
The forward is averaging 20.6 points on 58.0 percent shooting in his last 11 games.
Fatigue shouldn't be a factor for Miami, with no player reaching 36 minutes in Orlando. The Heat are 4-1 in the second half of back-to-back games.
The Raptors last won six in a row March 22-April 4, 2009. DeMar DeRozan is averaging 20.4 points during this win streak while Kyle Lowry is averaging 18.4 points and 10.6 assists.
Toronto, which hasn't defeated Miami since Jan. 27, 2010, is limiting foes to an average of 86.4 points in its last five games compared to 99.4 before the win streak.
"It's fun winning," forward Amir Johnson said. "Pretty much nobody has no worries, everybody's just on a cloud right now having fun, winning games. It's almost starting to feel kind of natural."
The Raptors held John Wall to 11 points to key Friday's 101-88 win at Washington. DeRozan scored 20 and Lowry had 19 and 11 assists.