D.C. United midfielder and United States international Paul Arriola left Saturday night's preseason exhibition at Orlando during the first half after he suffered a right knee injury.
Arriola, a 25-year-old midfielder later confirmed on Monday that he expects to be out "many months" with an ACL injury.
"A few days back on February 15th, as many know, I suffered an ACL injury to my right knee that will take months to recover from," Arriola tweeted. "As of now it is still unclear on a timeline of events as we consult with doctors and physicians to figure out what the next best step is for myself, my career, and my knee. I want to thank everyone for their kind messages and prayers. I love you guys and I know 100% that I will be back stronger than ever.
The news is a devastating blow for both D.C. and the player. The club saw the departure of Wayne Rooney this offseason but was expected to have a formidable attack with Arriola and the additions of Edison Flores, Julian Gressel and Yamil Asad.
Flores and Asad are also nursing injuries, so the long-term loss of Arriola could put the four-time MLS champions at an early disadvantage with the regular season starting on Feb. 29 against the Colorado Rapids.
Arriola, who joined D.C. from Liga MX club Tijuana in 2017, has also been a regular starter for the U.S. national team under coach Gregg Berhalter. Arriola has five goals in 33 international appearances.
The Associated Press contributed to this report.