Mickael Pietrus took a nasty spill on Friday night in Philly, and he’s been diagnosed with a concussion. There’s no timetable for his return to action as of yet. From the Boston Globe: “The Celtics were forced to use Avery Bradley at shooting guard Sunday because of injuries to Mickael Pietrus and Ray Allen. The move paid off, as Bradley scored 15 points in the first quarter against the Wizards and finished with a career-high 23 in the Celtics’ 88-76 win at TD Garden. Bradley may man the position for a while as Pietrus and Allen could miss multiple games. Pietrus has been diagnosed with a concussion, according to coach Doc Rivers, and the organization has not discussed when he will begin NBA-mandated tests before he can return. Pietrus has to pass a series of neurological tests and be cleared by a league-sponsored doctor. Pietrus was injured in the second quarter of the Celtics’ 99-86 loss to the 76ers Friday night, but was able to travel back to Boston Saturday. Pietrus did not attend Sunday’s game. ‘It’s a concussion and he’s not even ready to take the test yet,’ Rivers said. ‘We’ll just have to wait and see. He sounds great. I knew he had a concussion, but I was more worried about his neck. So we’re fortunate. I have no idea [when he will return], we haven’t talked about that.’”