Didier Drogba lost what could be the last match of his career, while Phoenix Rising was beaten 1: 0 by Louisville City FC in the final of the United League Football Cup.
The 40-year-old former Chelsea striker said this was his last season.
In April 2017, Drogba became one of the owners of Phoenix Rising in the US second division.
The owner of Berke Bakay thanked him for the "outstanding contribution to this beautiful sport" after Friday's defeat.
Drogba scored in each of the club's three play-offs on the way to his first USL Cup final.
"You have laid the foundation for something very special that we will all enjoy for years to come," Tweet Bakay.
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Before the final, Bakay told the BBC that Drogba would remain on the club board after retiring.
On the Phoenix Rising website last month, Drogba said he was not joking when he asked his opponents to give him a trophy so he could retire in peace.
He had promised to wear crampons again if he had no coveted trophy but he explained near the end of his message that this was his last season.
The club has not confirmed his retirement. Drogba scored 157 goals in 341 caps during his first assignment at Chelsea from 2004 to 2012, winning three Premier League and Champions League titles.
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After Shanghai Shenhua in China and Galatasaray in Turkey, where he won the Super Lig and Turkish Cup, Drogba returned to the Blues for the 2014-15 season, scoring seven goals in 40 matches and helping José Mourinho's side win the title.
He then spent 18 months at Montreal Impact before joining Phoenix.
He scored 65 goals in 104 matches for Ivory Coast and was named twice as an African football player this year.