The Boston Celtics beat the Toronto Raptors to take a 3-2 series lead in their Eastern Conference semi-final and leave the defending champions on the brink of NBA play-off elimination.

A stellar defensive showing in the opening quarter put the Celtics 25-11 up and they pushed on to a 111-89 win.

"The job isn't done," said the Celtics' Jaylen Brown. "We've got to come out and play with the same intensity."

The Celtics can seal the best-of-seven series in game six on Wednesday.

Raptors point-guard Kyle Lowry said: "They were very comfortable from the jump. We weren't as assertive as we should have been."

In the night's other game in Orlando, Florida, Paul George scored 32 points as the Los Angeles Clippers won a back-and-forth battle with the Denver Nuggets to take a 2-1 series lead in their Western Conference semi-final.

Denver led 78-67 midway through the third quarter and the lead changed hands nine times before the fourth quarter began.

"The game came down to one of the two teams was going to play some defence," Clippers coach Doc Rivers said.

"For three and a half quarters both teams were basically scoring and the last six minutes it was our defence."