Crawford was going to throw before the game and would likely pitch off a mound to test his back, according to Blue Jays manager John Farrell.
Farrell said Crawford came in Saturday more loose than expected and more than anything, the team wanted to get a gauge on his flexibility and movement.
"He felt something on one pitch and then bent over to stretch, which are abnormal movements, so we went out and checked him," Farrell said. "He wanted to get through it, but when he went to back up third base, you could tell when he was running that it was starting to clamp down on him.
"Last night has no bearing on his roster status -- he's day to day, and we will proceed accordingly."
Crawford has had this problem before, so the Blue Jays will take a cautious approach with him, although the injury doesn't appear to be serious.
The rookie has a 6.75 ERA over seven appearances with Toronto. He has also spent time in the Minors, at both Double-A New Hampshire and Triple-A Las Vegas, where he posted a combined 3.52 ERA over 7 2/3 innings of relief.