Former LA Galaxy and Seattle Sounders coach Sigi Schmid died on Tuesday aged 65.
Schmid, who won two MLS Cups during his career, stepped down from his role as Galaxy coach earlier this year.
His passing, due to a "personal health matter", was confirmed in a statement from his family on Wednesday.
We are deeply saddened to hear of the passing of former MLS head coach Sigi Schmid.— Major League Soccer (@MLS) December 27, 2018
Our thoughts are with his family and loved ones at this difficult time, and his legacy will continue to live on through the impact he's made on the game in the United States. pic.twitter.com/vGS7UX51Ey
In a separate statement, MLS commissioner Don Garber paid tribute to Schmid.
"Major League Soccer is devastated by the news of the passing of Sigi Schmid," he said.
"Sigi will go down as one of the leading figures in the history of our league. From Los Angeles to Columbus and Seattle, Sigi won more games than any coach in MLS history and led his clubs to multiple championships, including two MLS Cups and five Lamar Hunt U.S. Open Cups.
"Sigi's passion for soccer was unrivaled, and he was loved and admired by everyone in MLS.
"We deeply mourn his passing and send our heartfelt condolences to his wife Valerie, their children, and all of his loved ones."
R.I.P #SigiSchmid ....always one of my favorites;a good man,a good coach with a good heart...a good song,was Sigi. 😘— Ray Hudson (@RayHudson) December 27, 2018
Schmid won the MLS Cup with the Galaxy in 2002 before leading the Columbus Crew to the title six years later.
He guided the Seattle Sounders to the MLS Supporters' Shield in 2014 before returning to the Galaxy three years later.
I remember his intensity, and his kindness. If Sigi Schmid did nothing but turn UCLA into a powerhouse, he'd still be a legend. He added to his laurels in MLS and the USSF, but his greatest accomplishment is the love and respect that remains from those who knew him best.— Phil Schoen (@PhilSchoen) December 27, 2018
A two-time MLS Coach of the Year, Schmid compiled 240 regular-season wins – the most of any coach – and 26 post-season victories.
Schmid is survived by his wife Valerie and four children – Erik, Lacey, Kurt and Kyle.