BOSTON — Already ruled out of Friday’s game against the Chicago Bulls after removing himself from a practice session on Wednesday, Boston Celtics guard Marcus Smart said Friday that he will also likely miss Sunday’s game against the San Antonio Spurs as he continues to work his way back from a left ankle injury.

Smart said there isn’t a firm timetable for his return to game action, but he feels he’ll be able to return soon.

“You never know, some days I feel good, some days [the ankle] doesn’t,” Smart said. “I can’t really give you an exact date of when I’ll be back. I just know the way the progress is looking I’ll be back soon.”

Smart suffered a severe sprain and bone bruising after stepping awkwardly on a defender's foot while driving at the basket against the Indiana Pacers on Nov. 7. He said that the tenderness he felt during Wednesday’s practice was more a result of the bruising, which he has both on the inside and outside part of the bone.

Having not participated in Thursday’s team practice, Smart said he was feeling better on Friday.

“Right now it’s feeling pretty good,” Smart said. “I woke up yesterday morning with a little bit of swelling in it, but it’s going down, so that’s always good. I’m putting a lot more pressure on it than I was a couple of weeks ago.”

Smart said that the main thing that’s still causing him pain is cutting lines, perhaps one of the most pivotal elements of the guard's game.

“The type of player I am, I need to be able to cut with comfortably,” he said. “We’re trying to make sure we can work those kinks out and get me able to cut right.”

In the locker room before Friday's game, Smart initially had his ankle wrapped before removing it. At the time of his injury, the team announced his recovery timetable at 2-3 weeks, with Friday representing the three-week mark. Still needing time to recover, Smart admitted that it’s been frustrating to not be playing.

“You want to be out there,” he said. “That’s all your really know, to compete. Not being able to do that, it feels like you’re out of place.”

For his part, Celtics head coach Brad Stevens understands Smart’s frustration but is pleased that the rookie isn’t trying to rush himself back before he’s ready.

“He’s doing everything that he’s supposed to be doing, with regard to getting back,” Stevens said. "It’s frustrating for him, because it’s a little bit above the timeframe that we initially thought, a couple days. But I think that he’ll continue to work and hopefully be back -- we thought he’d be back [Friday], but [it will be] sooner rather than later.”