WASHINGTON (CN) – An onfield argument between two D.C. United teammates spilled over into a practice-field assault that left a promising young goalkeeper with a career-ending concussion, the injured player claims in court.

Charles Horton signed with the Major League Soccer team in February 2016 after a stint playing in two English soccer leagues. Horton played goal on the United States’ under-23 national team, and D.C. United hailed the 21-year-old as a “talented young goalkeeper” with a bright future in a press release after signing him.

On March 29, 2016, Horton left a team film session with Fabian Espindola, a forward Horton claims had a history of “violent conduct on and off the field.”

The two briefly rekindled an argument they had at a practice two weeks earlier, but Horton told Espindola he did not want to continue the fight and “turned away,” according to a complaint filed Monday in D.C. Superior Court.

Espindola allegedly then elbowed Horton in the left temple and had to be separated from the goalkeeper by teammates and staff. It wasn’t the first time Espindola had elbowed a fellow player. As Horton notes in the complaint, Espindola was ejected from an MLS game in July 2015 for hitting an opposing player in the head.

Espindola was also suspended six games in 2014 after he shoved a referee during a match, according to the complaint and a Washington Post report from the time.

Horton claims he felt the early symptoms of a concussion immediately after Espindola hit him, including “dizziness, shakiness” and sensitivity to light. Despite this, the team did not put him in the MLS concussion protocol and he practiced shortly after the alleged assault, according to the 18-page complaint.

But the symptoms worsened that night to the point where he wasn’t able to practice the next day. It wasn’t until May, more than a month after the elbow, that Horton was cleared to play again.

He broke a finger while training with a lower club and missed the rest of the 2016 season. He continued to have “post-concussive symptoms,” which he says has prevented him from getting his job back on D.C. United. The team decided later that year not to renew his contract, according to the complaint.

“Due to the severity of his ongoing post-concussive neurological symptoms, which directly inhibited his ability to perform at a level necessary to continue his professional career, Mr. Horton was forced to official retire from professional soccer,” Horton claims.

Horton is represented by Ashcraft Gerel attorney Palmer Foret and lists Espindola, D.C. United Manager Benjamin Olsen, D.C. United and Major League Soccer as defendants in the case. He seeks compensatory and punitive damages to be determined at trial for assault and battery.

Foret says Horton’s retirement “certainly wasn’t a voluntary” one and that the former keeper is still experiencing symptoms from his concussion to this day.

D.C. United, which traded Espindola in July 2016, also did not respond to a request for comment. Espindola’s current team, the Mexican squad Club Necaxa, also did not respond to a request emailed to the team on Wednesday.