Celtics back in Boston, back at practice for 76ers updated 1:08 p.m. (AP) - The Celtics player who needs a break the most this postseason isn't 34-year-old Paul Pierce, who's nursing a knee injury. Or 36-year old Ray Allen, who's got bone spurs in his ankle. Or even Kevin Garnett, who turned 36 on Saturday but is playing like he did a decade ago. It's Avery Bradley, 21, who is determined to stay on the court despite a left shoulder that has popped out of its socket four times so far during the season. "He is a guy who wants to be out there; a guy that wants to win and do anything he can to help," Pierce said. A lot of young players would probably sit down and worry about their futures or careers or contract situations. ... Hopefully he doesn't have any long-term injuries due to the fact that he's playing. A first-round draft pick who did not appear in the playoffs as a rookie last year, Bradley moved into the starting lineup when Allen was injured and remained there even after the future Hall of Famer returned. Bradley dislocated his shoulder in Game 3 of Boston's first-round series against Atlanta, but has not missed a game because of it. "He's dealing with stuff and it's tough," Celtics coach Doc Rivers said on Sunday before practice, which Bradley sat out. A lot of people would not be playing, and the only reason he is is because he wants to. I am concerned at some point that he may not be able to anymore. We don't know what game that is. ... Tomorrow could be his last game. The Celtics resume the Eastern Conference semifinals against the Philadelphia 76ers with Game 5 on Monday night. The series is tied 2-2 thanks to the Sixers' comeback from an 18-point, third-quarter deficit to win Game 4 92-83. "It's a swing game, but it's a swing game for both teams," Rivers said. Game 5s and Game 7s are pretty much the same. Game 6 is Wednesday in Philadelphia, with a seventh game back in Boston on Saturday, if necessary. With two days off between the fourth and fifth games, Rivers gave his aging team the day off on Saturday before returning to practice on Sunday. Bradley did not participate in the workout, but Allen was on the court shooting jumpers 30 minutes early and Garnett joined him soon after. Rivers said Bradley's shoulder has popped out at least four times during this season. On Friday night, it popped out but popped right back in. "It's crazy," Rivers said, adding that the injury is keeping Bradley from driving to the basket. Listen: It's a tough thing that he's going through. A lot of players would not be playing.