It's been three weeks since Marcus Smart was injured, and he could still have up to three weeks left in his recovery.

While speaking to the media Sunday ahead of his team's 112-90 win over the Bucks in Game 1 of the conference semifinals, Celtics coach Brad Stevens confirmed the guard is unlikely to return before the initial timeline predicted.

Smart suffered an oblique injury late in the regular season and was originally expected to be out for four to six weeks. However, he began running on a treadmill last week and also participated in lighting shooting drills.

"He’s in there doing some core work," Stevens replied when asked for a status update, via MassLive.com. "That’s my update for the day. I really don’t. I don’t have any update, because I haven’t asked timeline-wise, they just keep telling me he’s improving. I haven’t gotten anybody come up and say, ‘Hey, he might play in Game 3.’ I don’t see any way that he’s available until whatever his timeline hits that we thought initially. Four to six (weeks), and I said at the start, four seems awfully aggressive."

Earlier this month, the 25-year-old discussed the rehab process and how difficult it has been on him.

"It’s tough, tough from that standpoint because our whole lives we’ve been taught to fight through pain, to fight through injuries, to fight through anything, adversity, obstacles," Smart said at the time. "You get on that court you’re taught to go, go, go. You know the old saying, you’re going to feel better than you really are soon.

"Sometimes your mind actually forgets that you’re hurting, and you try to do things. You have to remind yourself, slow it down, take it easy, and that’s the hard part because you want to go, go, go but you can’t."

Smart finished the regular season averaging 8.9 points, 2.9 rebounds and four assists. He shot 42.2 percent from the field and 36.4 percent from 3-point range.

The Celtics swept the Pacers in their first-round series and got an early lead on the Bucks as the second round started.

Milwaukee will host Boston for Game 2 at 8 p.m. ET Tuesday.