D.C. United captain Steve Birnbaum suffered a concussion and no other injuries in a head-to-head collision late in Saturday’s match against the New York Red Bulls, General Manager Dave Kasper said Monday.

Birnbaum was injured in the second minute of stoppage time when, in a three-man challenge for Jared Jeffrey’s long ball in United’s attacking end, the back of Red Bulls defender Damien Perrinelle’s head smashed into Birnbaum’s right temple.

Medical staff rushed to his side and called for a stretcher. He was taken to the locker room and later to a New Jersey hospital for additional evaluation and testing. While the team returned to Washington late Saturday, Birnbaum stayed at the team hotel with a staff member, Kasper said. He traveled home Sunday. “He’s feeling better,” Kasper said.

Birnbaum, a U.S. national team center back in his fourth MLS season, will undergo standard concussion protocol before he is permitted to resume workouts. He seems unlikely to play this Saturday against the New England Revolution at Gillette Stadium in Foxborough, Mass. The following weekend, United will visit Atlanta United.

With Birnbaum likely sidelined, Coach Ben Olsen could partner Bobby Boswell with Kofi Opare, who made his season debut Saturday in replacing his injured teammate. Another option is Sean Franklin, who started the first three matches at center back before losing the job to Boswell. On Saturday, Franklin started at right back, his natural position, because Nick DeLeon was needed at left wing in place of Patrick Nyarko (hamstring).

DeLeon suffered a groin injury in the first half Saturday and, after trying to play through it after halftime, came off in the 47th minute. Sebastien Le Toux entered the match. The club will evaluate DeLeon and Nyarko throughout the week.