WALTHAM, Mass. — Boston Celtics guard Jaylen Brown is doubtful for Game 1 of the Eastern Conference semifinals against the Philadelphia 76ers with a strained right hamstring, coach Brad Stevens said, while adding that he could return later in the series.

Stevens said Brown still had some soreness on Sunday, a day after the Celtics eliminated the Milwaukee Bucks and a day before the second-round opener. Brown had said he was going to have an MRI, and Stevens said tests were negative.

"It looks like it could be something that allows him to play as the series goes on," Stevens said.

The No. 3 overall pick in the 2016 draft, Brown averaged 14.5 points and 4.5 rebounds per game this season. He left Saturday night's clincher against the Bucks in the first quarter; the team announced that he was available to return, but Stevens decided to play it safe.

Brown said afterward he was told it was a Grade 1 injury — the least severe kind. He was put on anti-inflammatory medication.

"Whatever it takes, I wouldn't miss this series for the world," Brown said Saturday night.

The Celtics are already without stars Gordon Hayward and Kyrie Irving, as well as Daniel Theis.

"We don't think about what's happened throughout the season," center Aron Baynes said. "We have that 'next man up' mentality. We'll miss Jaylen; he's definitely hard to make up for. It's just all being able to collectively do it."