The Miami Heat’s mission to reach the NBA Finals has become a bit tougher, as starting guard Gabe Vincent has been ruled out for Thursday’s Game 5 of the Eastern Conference finals against the Boston Celtics because of a sprained left ankle.

Vincent was injured with just over eight minutes left in Miami’s Game 4 loss when he landed awkwardly and rolled his ankle while catching the ball after Jayson Tatum blocked his shot.

He then went to the locker room and got his ankle taped and was able to return with just under five minutes to play.

Thursday morning, Vincent went through a workout but Heat coach Eric Spoelstra said he's not healthy enough to take the court in Boston.

The four-year veteran finished with 17 points in Tuesday’s 116-99 loss after leading the Heat with a playoff career-high 29 points on 11-of-14 shooting in Sunday’s 128-102 victory that gave Miami a 3-0 lead in the conference finals.

Vincent has started each of Miami’s first 15 playoff games and is third on the Heat in postseason scoring at 13.1 points per game behind Jimmy Butler (29.9) and Bam Adebayo (17.6).

His 36 3-pointers this postseason are the most among all Heat players and he’s been solid from the foul line, making 25 of 28 free throws (89.3 per cent).

With Vincent out, 37-year-old Kyle Lowry is expected to move into the starting lineup.

The 17-year-veteran is averaging 9.2 points, 4.5 assists and 3.3 rebounds off the bench for Miami this postseason.