The Portland Timbers, who clinched a playoff spot Sunday, will be without their joint leading goal-scorer for an undetermined period of time.
Forward Brian Fernandez voluntarily entered MLS's substance abuse and behavioral health program, the team and league announced Monday.
While no details were released regarding the cause of Fernandez's move, the 25-year-old Argentinian has dealt with substance-abuse issues in the past.
The Timbers wrote in a statement, "Our number one priority is Brian's emotional and physical well-being. Our thoughts are with him."
Fernandez missed the regular-season finale Sunday due to a red-card suspension as Portland earned a 3-1 victory over the San Jose Earthquakes to wrap up a berth in the playoffs. The Timbers will play Real Salt Lake in a Western Conference quarterfinal game on Oct. 19 in Sandy, Utah.
In his first season for Portland this year, Fernandez tallied 11 goals in 19 games (16 starts). Jeremy Ebobisse also had 11 goals for the Timbers in 34 games (25 starts).
The Timbers acquired Fernandez from Mexico's Club Necaxa in May for a team-record fee of $10 million to $12 million.
In May 2015, while Fernandez was playing for Argentina's Racing Club, he tested positive for cocaine and subsequently served a three-month suspension.