Toronto FC forward Jozy Altidore exited Saturday's game against the New England Revolution with what appeared to be a hamstring injury.
Altidore, who saw his 2014 World Cup campaign end during the United States' opening match due to a hamstring tear, left the game in the first half.
Altidore has scored five goals this season for Toronto FC, which entered Saturday's match in sixth place in the Eastern Conference with nine points. The U.S. international joined Toronto ahead of this season from English Premier League club Sunderland.
The U.S. men's national team is scheduled to play at the Netherlands and Germany in early June. Altidore's injury jeopardizes his potential selection to Jurgen Klinsmann's team for the trip to Europe.
Prior to Saturday, Altidore had scored three goals in his last three games, including a two-goal effort on April 26 against Orlando City.
- Stanley Kay