The team announced Bryant's injury after the Lakers' locker room had cleared out following their 113-103 loss to the Bucks on Thursday night.
Bryant spent a large amount of time in the trainers' room of the BMO Harris Bradley Center and left the arena using one crutch and not putting any weight on the foot.
Entering Thursday's game 35 points shy of passing Wilt Chamberlin for fourth all-time in scoring, Bryant scored 30 points against the Bucks, but shot just 6 of 17 from the field.
There was more bad news for the Lakers on Thursday. Point guard Steve Nash left the game with 5:13 left in the third quarter and didn't return.
"Yesterday, last minute of the game his back and hamstring got fired up on him," Lakers coach Mike D'Antoni said. "He toughed it out at first. I could tell he was hurting. I just didn't have the heart to put him back in. He wanted to go back in but it wasn't fair to him. He was hurting."
Nash said it was more of a spasm in his hip that was bothering him Thursday. He said the hamstring injury occurred against Golden State on Monday and he overcompensated Wednesday against Minnesota and the hip flared up.
"I wanted to keep playing but I think Mike (D'Antoni) and (Lakers trainer) Gary (Vitti) didn't want to risk doing something that could cause longterm damage."
Nash was then asked if he'd be able to play Saturday against the Kings.