River Plate star Gonzalo "Pity" Martinez has confirmed he will join MLS side Atlanta United.
Martinez helped River to Copa Libertadores success by scoring in Sunday's final second-leg win over Boca Juniors.
River's title came just one day after Atlanta earned a trophy of its own, with the club defeating Portland 2-0 in Saturday's MLS Cup final.
The Copa Libertadores final second leg, which was suspended twice in November, was finally played in Madrid on Sunday with River running out 3-1 winners, clinching a 5-3 aggregate success.
Boca went ahead in the first half thanks to a brilliant Dario Benedetto goal, but Lucas Pratto levelled for an improved River in the second period, ultimately forcing extra time.
After Wilmar Barrios was sent off for a second booking early in the additional period, Juan Quintero's stunning strike put River ahead and Martinez wrapped things up right at the end.
It proved to be a fitting end to the game for the winger, as he announced his departure shortly after the match ended.
"I want to inform the fans that in January I will not continue [with the club]," Martinez told TyC Sports. "It is a very difficult decision for me, but the road continues.
"I think that I gave the fans what they deserve and it is everything that they believed in me. I am going to play the Club World Cup."
Martinez then confirmed that he would be joining the newly crowned MLS champions, having failed to generate enough interest for a possible move to Europe.
"[Atlanta] is the club that trusted in me," Martinez said. "European clubs didn't trust [in me] in the moment.
"I thought about it a lot with my family, with my representative. It's a league that's grown a lot and I hope to continue making history with this club."
The 25-year-old has only ever played his football in Argentina, having signed for River from Huracan in 2015.
His good form at club level led to his senior international debut in September, with Lionel Scaloni handing him his first appearance for his country in a friendly against Guatemala.