Two days after beating the Celtics 96-92 in an overtime thriller in Boston to stay alive, the Magic delivered a confident display on their home court to trail 3-2 in the best-of-seven series.
Guard Jameer Nelson top scored for Orlando with 24 points while muscular center Dwight Howard weighed in with 21 points, along with 10 rebounds and five blocked shots.
Rasheed Wallace contributed 21 points to lead the way for Boston, who had appeared to have the series firmly in control after winning the first two games in Orlando.
Game Six is in Boston Friday when the Celtics need just one more win to advance to the NBA finals.
"It was our best offensive night of the series," Orlando coach Stan Van Gundy told reporters after his team had shot slightly better than 52 percent from the floor.
"Obviously in Game Six we will need to be even better at both ends. We have a huge, huge challenge in front of us but it's a challenge we worked hard to get to."
No NBA team has ever won a playoff series after losing the first three games but Nelson said the Magic were banking on pulling off a miracle through sheer self-belief.
"We just all believe," he added.
"We know we can do it one game at a time. We know we didn't play our best in the first three games, but that's behind us. We are trying to make history."
A difficult night for the Celtics became even worse when they lost starting center Kendrick Perkins shortly before the end of the first half when he was ejected after picking up two technical fouls, his sixth and seventh of the postseason.
Unless the league rescinds one of the technicals, Perkins will face a mandatory one-game suspension.
The Celtics raced 5-0 up early on before the Magic took control with a scintillating three-point display to lead 31-27 after the first quarter.
Guard JJ Redick and Mickael Pietrus each added a pair of three-pointers as Orlando charged 14 ahead midway through the second period before holding a 57-49 advantage by half-time.
The Celtics were also deprived of Perkins's replacement, Glen Davis, when he suffered concussion after being accidently struck by Howard's elbow just before the end of the third quarter.
Leading 84-75 going into the final period, the Magic steadily pulled even further away to keep alive their hopes of reaching the NBA finals for a second year in a row.
"They played a great game tonight," Celtics coach Doc Rivers said of the Magic. "They are a great team when they get a lead because then those threes (three-pointers) are easy. I never thought we applied any real pressure."
