Avery Bradley, Ray Allen play

BOSTON -- Boston Celtics shooting guards Avery Bradley and Ray Allen will both play in Sunday's Game 4 of an Eastern Conference quarterfinal series against the Atlanta Hawks at TD Garden.

Bradley dislocated his left shoulder in Friday's Game 3, but was cleared by doctors about an hour before tipoff. He'll start, but Celtics coach Doc Rivers admitted he'd keep a close eye on the second-year guard. Allen, who played 37 minutes Friday on a balky right ankle in his first game in nearly a month, is there for depth as the ankle responded well after taking Saturday to rest.

"[Bradley is] going to go; we're just going to kind of see how he feels and just go from there," said Rivers. "It's a concern -- a concern tonight and moving forward as well. But we're just going to throw him out there -- we just got the OK about 10 minutes ago -- so he's just going to try to see how it feels."

Rivers said the shoulder had dislocated on multiple occasions this season, but had always gone back into place. This time around it proved more difficult.

"It's happened three or four times and it's come back in," said Rivers. "That was the only scary part, that it didn't go right back in. I guess each time it comes out, you lose strength and you can't play again until the strength returns. But he's ready to go."

Rivers said it was far too early to discuss whether the shoulder would need surgery in the offseason.

As for Allen, he admitted his ankle was throbbing during Saturday's off day, but responded well enough to treatment to allow him to get back on the floor Sunday.

"Even when I walked out [of the Garden on Friday], after you ice and you walk out, my ankle just felt -- I had to walk sideways, it just felt that tough and that achy. [Saturday], I couldn't do anything. It was throbbing. I got in and I got treatment. Just all day, it felt like I was pulling my leg around. But I woke up this morning and I was back right where I hoped I'd be. That's just the cost of doing business, I guess."

Was Allen worried he might not play Sunday?

"No. Maybe a slight bit," he admitted. "I'm thankful that we didn't have a back-to-back."

With the Atlanta Hawks facing what amounts to a must-win situation Sunday, Al Horford was activated by the team and checked in midway through the first quarter.

Horford tore his left pectoral muscle in January and was not expected to be back for this series, but with Atlanta's season hanging in the balance, he decided to give it a go off the bench.

Josh Smith, who missed Game 3 with a left knee injury, is back in the starting lineup in Game 4.

Zaza Pachulia and Jerry Stackhouse are the inactives for Atlanta.

Information from ESPNBoston.com contributor Greg Payne was used in this report. ESPN's Ric Bucher contributed to this report.