(CBS) An afterthought for the Bulls less than a week ago, Isaiah Canaan will now play a large, pivotal role for the Bulls in their most important game of the season to date.

Canaan will start at point guard for Chicago in Game 5 at Boston on Wednesday night with the first-round series tied 2-2, coach Fred Hoiberg said Monday. This news came a day after Canaan unexpectedly played 34 minutes for the Bulls off the bench in a Game 4 loss with young point guards Jerian Grant and Michael Carter-Williams continuing to be ineffective in the absence of the injured Rajon Rondo. Prior to Sunday, Canaan had played just 21 minutes since the All-Star break while inactive/receiving a “Did not play — coach’s decision” designation in 22 games.

Canaan had 13 points on 4-of-10 shooting, three assists and no turnovers Sunday, and Hoiberg also lauded his defense. Game 5 will be his first start of the year, Canaan played in 39 regular-season games, all in a reserve role.

“I really thought he did a good job picking up the ball and pressuring the pick-up point most of the night, a full 94 feet, some picking up right over half court,” Hoiberg said. “But I thought he did a good job of that, with his initial ball pressure. Obviously, we need to get off to a much better start if we want to have any chance of winning another game in the series.”

Rondo has been ruled out of Game 5 as he continues to recover from a fractured right thumb after dealing with a late-season right wrist injury. His hard cast has been removed but is still in a splint as the wrist has improved, but Rondo’s thumb is still the problem, Hoiberg said. He’s expected to be re-evaluated later this week.

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