Former U.S. international Davy Arnaud announced his retirement on Thursday because of lingering concussion symptoms.
Arnaud, 36, was set to begin his third season with D.C. United, but instead will now join their coaching staff.
He started 21 games last season but suffered a concussion in practice in August.
Arnaud told the Washington Post that he still had a "drunk, dizzy feeling."
Thank you, @d_arnaud22, for a fantastic career & passion on & off the field.
- D.C. United (@dcunited) March 3, 2016
"It's tough to come to terms with it because I love playing," he said. "This is what I do and this is what I love to do. I am not young and naive and stupid anymore.
"When you are younger, you think you can work through it. But the ultimate decision is the right one."
The midfielder played 14 seasons in Major League Soccer -- 10 with Kansas City and two with Montreal before joining D.C. -- making 351 appearances, the fifth most in MLS history. He scored 50 goals with 46 assists.
Arnaud made seven appearances with the U.S. national team and scored in the 2007 Gold Cup against Haiti.