Leonard got off an attempt just before the shot clock expired to put the Raptors up 94-90 against the Philadelphia 76ers, before Danny Green settled the tie with four free throws.
Green was one of five Toronto players to make double digits, with Marc Gasol scoring 16 and Kyle Lowry finishing with 14 as the Sixers' run of two wins came to a close.
Joel Embiid could only manage 11 points for Philadelphia, while Jimmy Butler scored 29 and JJ Redick had 19.
The Portland Trail Blazers also lost on their home court as a 116-112 victory for the Denver Nuggets saw the series tied up at 2-2.
The damage was done in the third quarter, where the Nuggets limited Portland to only 14 points as Denver took a 84-77 lead into the final frame.
Jamal Murray finished the game with 34 points, while Nikola Jokic added 21 points, 12 rebounds and 11 assists for his fourth triple-double of the playoffs, while CJ McCollum top scored for Portland with 29.