Leeds United midfielder Tyler Adams faces an extended period on the sidelines after having surgery on a hamstring injury.
The 24-year-old was injured in training earlier in March and was forced to withdraw from international duty with the United States.
Adams has made 26 appearances in all competitions for the Whites since joining from RB Leipzig in the summer.
Leeds are 14th in the Premier League, two points above the relegation zone.
Javi Gracia's side face leaders Arsenal on Saturday (15:00 BST) and could also be without defender Max Wober and midfielder Wilfried Gnonto, who were both injured on international duty with Austria and Italy respectively.