ATLANTA – Avery Bradley suffered a severe right hamstring strain Saturday night and is “very unlikely” to return to Boston’s lineup during the team’s first-round series against the Atlanta Hawks, according to Brad Stevens.

Stevens broke the news Sunday afternoon, shortly before the Celtics began practice at Georgia Tech’s basketball facility.

“Avery has a pretty significant strained hamstring,” the coach relayed. “I would say he would be doubtful for any of the remainder of the series, certainly very unlikely Tuesday night.

“Obviously he’ll continue to get treatment around the clock and go from there. So I would say very unlikely the rest of the series.”

Bradley’s injury is a substantial blow to the Celtics, who fell 102-101 during Saturday’s Game 1. Bradley was the team’s second-leading scorer during the regular season with an average of 15.2 points per game and is one of the team’s leading 3-point threats, having hit 36.1 percent of his 3s during the regular season. He is also regarded as one of the premier on-ball defenders in the league.

Boston played six games this season without Bradley and went 3-3 during those contests, including a 106-93 win over the Hawks on Nov. 13. Although six games is a small sample size, Stevens believes the regular season prepared the Celtics to compete at a high level without their starting shooting guard.

“We’ve had [injuries] with significant people on our team enough that we at least have an idea of how we’ll proceed forward,” Stevens said.

The coach then singled out two players who will be leaned on heavily during Bradley’s absence.

“I think the one thing about having a guy like Avery out is you’ve got guys like Marcus Smart and Evan Turner who have played a starter’s role for us all year off the bench,” said Stevens. “Both of those guys are going to be critically important to replacing Avery or adding to what they normally do.”

Smart put forth one of his best all-around performances of the season during Game 1. He finished with 15 points, five rebounds, two assists, two steals and a block while hitting half of his shot attempts and three 3-pointers.

“I thought Marcus was really good last night,” Stevens said of the second-year guard. “He made shots, he made plays off the dribble, he’s one of our better perimeter defenders, and we need him to continue to be able to play in a number of different places in Atlanta.”

Turner also played well during his 34 minutes of action. He logged 10 points, eight rebounds, five assists, a steal and a block while committing only one turnover.

It appears that either Smart or Turner will slide into the starting lineup while Bradley is sidelined. Stevens also hinted that he may opt to play more traditional lineups, with two big men and three guards/wings, throughout the remainder of the series.

Other players who are likely to see increased playing time are rookie guards R.J. Hunter and Terry Rozier, and big man Tyler Zeller. Hunter logged three minutes of playing time during the first half of Game 1. Rozier and Zeller, meanwhile, did not appear in the contest.

It is no secret that all of those players will need to rise to the occasion if Boston is to advance to the next round without the services of one of its most reliable two-way players. If they are able to do so, it is conceivable that Bradley could return to the lineup before Boston’s season comes to an end.