Celtics may be without Jaylen Brown again in Game 2

The second-year swingman is listed as doubtful against the Philadelphia 76ers Thursday night because of a right hamstring strain.

WALTHAM – They jumped from a seven-game opening-round playoff series right into the second round with just one day off this week.

So after defeating the Philadelphia 76ers in Game 1 of the Eastern Conference semifinal round Monday night, the Celtics welcomed have a free day on Tuesday with no game, practice or film session on the schedule.

“I went down to Newbury Street and did a little shopping, so that was good,’’ said guard Terry Rozier.

“I think it was good for our team,’’ said coach Brad Stevens. “We ended the season with back-to-back (games) and then we went straight into the playoffs and every day was either a film, walk-through or practice.

“So that was the first day where it was, come in and get treatment but otherwise. you need to go for a walk outside and take a deep breath.’’

And after a much needed break in the action, the Celtics were back at their training facility Wednesday afternoon for a light workout in preparation of Game 2 against the 76ers Thursday night at the TD Garden (8:35, TV: TNT; radio: WBZ-FM/98.5).

The Celtics find themselves in a position where they can open a 2-0 series lead over the Sixers, but they may have to play once again with Jaylen Brown.

After missing the series opener with a right hamstring strain, Brown is listed as doubtful by Stevens, though that could change depending on how the second-year swingman reacts to a Thursday morning workout.

The Celtics survived the second half of Game 7 against the Milwaukee Bucks on Saturday night and Game 1 against the 76ers without Brown, but his presence is going to be needed against shooters like JJ Redick and Marco Belinelli in this series.

While Brown tried to talk his way into playing the first game, the Celtics are urging him to be cautious, knowing that a re-aggravation might keep him out for the rest of the playoffs.

“The bottom line is this hamstring injury is not terrible,’’ said Stevens before practice Wednesday. “It’s not a long-term thing. It shouldn’t linger if he comes back at the right time.

“But you could make it worse if you don’t come back at the right time if you have to guard JJ Redick and Marco Belinelli. He’s going to have to do that, so this is a good test to know when you’re going to be back.

“This is not just about running, it’s about running at full speed all the way around the court, so it’s a real test. Jaylen wants to play, but he’s smart about it. He trusts our trainers.’’

Brown, who was not available for comment, went through a workout prior to practice with assistant coach Micah Shrewsberry and the strength training staff.

“I have not gotten a report on how it went,’’ said Stevens. “It looked pretty good, but I doubt that he will do much in practice. He’ll be reassessed (Thursday), but I know that he’s doubtful.’’

Should Brown not be available, Marcus Smart will get the start again in the backcourt alongside Rozier.

Smart has played four games since returning from right thumb surgery after tearing a ligament on March 11. During Game 1 against the Sixers, Smart took a hit on the thumb just before halftime.

He said that a different kind of splint will be used for Game 2 to help Smart have more use of the thumb.

“It was a little sore,’’ he said. “It’s fine. I’m good to go for tomorrow. (Getting hit) was the biggest risk coming back. That’s the reason I have the split on to protect it from those incidents.

“We have a few different ones that we’re trying out. The one last game was really big into my thumb and I couldn’t catch the ball the way I wanted to. I couldn’t get a grip on it, things like that. We’re working on cutting it down.’’

The Celtics used an eight-man rotation to beat the Sixers, who had been 20-1 in their previous 21 games, and they keep covering up for missing players.

“I think it starts first and foremost with the players,’’ said Stevens, “and secondly, one of the things (president of basketball operations) Danny (Ainge) has really hit a home run with among the many things is that in all of our moves, it seems like competitiveness, resiliency, a desire to be a part of something bigger than yourself have really weighed heavily in all of those decisions.

“If you look at all the draft picks or pickups or trades, we’ve got a real strong locker room. They’re in it for each other. They’re in it for the right reasons. That gives you a little bit more a feel of, OK, the next man can step up and cover when somebody is down. I think that’s what it boils down to.’’