D.C. United midfielder Paul Arriola suffered a serious knee injury during Saturday night's 1-0 preseason win against Orlando City SC.
The 25-year-old American left the match in the 30th minute with a suspected torn right ACL. The team said he would undergo an MRI exam Sunday.
"Doesn't look good," coach Ben Olsen told the Washington Post.
"Please send all of your prayers to my brother," fellow D.C. United midfielder Russell Canouse tweeted.
Arriola had six goals and two assists in 29 appearances last season, with 28 starts. He has 14 goals and 12 assists in 68 matches (64 starts) since his 2017 debut.
D.C. United open their 25th MLS season at home against the Colorado Rapids on Feb. 29.
--Field Level Media