DeRozan, who had entered the game averaging just 13.3 points, turned on the style as the Raptors fought back from 13 points down to seal a win which gives them a 3-2 lead.
Toronto had found themselves staring down the barrel of a home defeat after Indiana raced into a 90-77 lead in the third quarter.
But a 15-2 Raptors points blitz in the opening 5 mins 29 sec of the fourth quarter hauled the home side back into the contest with rookie Norman Powell scoring a monster dunk to tie it 92-92.
DeRozan then stepped up to drain a three-pointer to give the Raptors their first lead as Toronto held on for a pulsating win.
Pacers star Paul George had a game-high 39 points including eight rebounds and eight assists while George Hill added 15 points and Myles Turner had 14.
George bemoaned the Pacers’ failure to hang on for what would have been a potentially pivotal road victory.
“We didn’t make enough plays, that is what it came down to in the fourth quarter,” said George. “We have to put this (game) away. Friday (Game 6) is a new day and we have to get a win — it’s a must win. It’s awful to have a chance to win on the road and then come back home, but we failed to live up to the moment.”
The Pacers had appeared to be firmly in control after opening up a 61-52 halftime lead.
Indiana had looked the more polished side throughout the opening half, with George scoring 22 of his points in the first two quarters.
Toronto had lagged 35-20 after the first quarter following Indiana’s freescoring start. George led the Pacers scoring with 12 points and four assists in the quarter while Hill added nine points.
In Tuesday’s other game, Atlanta also took a 3-2 series lead after a blowout 110-83 win against the Boston Celtics.
Atlanta’s Mike Scott top scored after weighing in with 17 points off the bench as the Hawks hassled the Celtics into 19 turnovers in what rapidly became a rout.
The victory means Atlanta lead 3-2 in the best-of-seven series heading into Game Six in Boston on Thursday.
It was a night to forget for Celtics point guard Isaiah Thomas who was jeered at every turn by a fiercely partisan Hawks crowd.
Thomas, who finished with dismal numbers of seven points from 3-of-12 shooting, limped off the court in the fourth quarter after appearing to roll an ankle.
A rollercoaster series has seen Boston repeatedly claw back big deficits to overhaul Atlanta.
But their luck ran out on Tuesday as Atlanta cut loose in the second and third quarters to leave Boston scrambling to recover.
The Celtics had started brightly, compiling a healthy 29-19 lead at one point in the first half.
But a 28-10 run by the Hawks helped the home team into a 47-39 lead at half-time.
Boston attempted to get back into the contest after the break, but Kyle Korver, Scott, Paul Millsap and Dennis Schroder all drained threes during a frenzied burst of scoring to put Atlanta 22 points clear.
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