Darlington Nagbe will miss the next two to three months with a groin injury, Atlanta United announced on Tuesday.
Nagbe, 27, was injured in the second half of Atlanta's 1-1 draw with the Portland Timbers on Sunday. Atlanta's timeline would allow Nagbe to return in the run-up to the playoffs.
The attacking midfielder, who has played in every one of Atlanta's game this season, was one of six United players named as MLS All-Stars in the "Fan XI" on Sunday.
"Atlanta United today announced that midfielder Darlington Nagbe will miss two-to-three months with a right adductor injury," a club statement said.
Atlanta acquired Nagbe from the Timbers in a blockbuster trade in December that saw the team shell out as much as $1.65 million in allocation money for the U.S. international.
Julian Gressel or Kevin Kratz could move into Nagbe's place in midfield for Atlanta, which is already without full-back Greg Garza after a shoulder injury.
Atlanta also moved to sign a new midfielder on Tuesday, completing a deal for 23-year-old Argentine Eric Remedi from Banfield, who will be eligible to play after the transfer window opens on July 10.