D.C. United’s Steven Birnbaum out with knee injury

United will begin the regular season Feb. 24 against New England at Audi Field. Birnbaum is also expected to miss trips to Portland and Cincinnati and perhaps sit out Lionel Messi’s visit to Washington with Inter Miami on March 16.

Entering his 11th season, Birnbaum is third on the club’s all-time list for regular season appearances with 248, trailing Jaime Moreno (340) and Bill Hamid (279).

He has captained the team for several years, but new coach Troy Lesesne has yet to announce this year’s leadership group.

Last season, injuries and coaching decisions limited Birnbaum to 22 appearances (20 starts).

He is the only experienced center back returning from last year’s squad following the departure of Donovan Pines (now with English club Barnsley), Derrick Williams (Atlanta) and Brendan Hines-Ike (Austin).

This winter, United began filling the void by trading for Lucas Bartlett (St. Louis) and Christopher McVey (Miami). This week, it acquired Conner Antley from second-division Tampa Bay; he plays primarily on the right side but has experience in the middle.

Matai Akinmboni, a highly regarded 17-year-old homegrown player, seems poised for significant playing time after starting two league matches last year. Hayden Sargis, 21, and rookie Garrison Tubbs are also in the mix.

McVey and Bartlett partnered against Al Ettifaq last Friday, the final tuneup in Saudi Arabia. United will close the preseason schedule Saturday at Dallas.

Meanwhile, defensive midfielder Russell Canouse is battling an ankle injury and might miss the opener, a person close to the team said. He has not played since the first preseason game. Canouse, entering his eighth season in Washington, had been projected to start alongside Finnish newcomer Matti Peltola.

United will post its first official injury report next Thursday.

Notes: Guidehouse, a McLean-based consulting firm acquired this winter by Bain Capital, is United’s new jersey sponsor, replacing XDC Network, a blockchain company whose logo appeared the previous two seasons. The five-year deal is worth about $7 million annually, one person familiar with the negotiations said.