Jozy Altidore will miss 6-8 weeks with a hamstring injury, ruling him out of playing at the Copa America with the United States this summer.
Toronto FC announced the diagnosis on Monday after the striker was hurt on Saturday against the Vancouver Whitecaps.
Copa America, scheduled to be held across the U.S. from June 3-26, will end before the earliest date by which it's estimated that Altidore could return.
Altidore, who has yet to score for Toronto FC in this season, was hurt while taking a penalty that was saved.
The 26-year-old also injured a hamstring against Jamaica in the 2011 CONCACAF Gold Cup and missed the final, then had another hamstring injury during the Americans' 2014 World Cup opener against Ghana and was sidelined for the rest of the tournament.
A hamstring injury last year caused him to be out of shape for the 2015 Gold Cup, and he was dropped from the squad for the knockout rounds, where the Americans lost to Jamaica in the semifinals.
Altidore was among the Americans' 40-man preliminary squad for the Copa. U.S. Soccer must submit a final 23-man squad from that list by Friday.
The other forwards on the preliminary squad are Clint Dempsey, Ethan Finlay, Jordan Morris, Christian Pulisic, Chris Wondolowski, Bobby Wood and Gyasi Zardes.
Earlier on Monday, the U.S. named a 22-man squad for a training camp this week in Miami ahead of a friendly against Puerto Rico, though that includes players who will not be involved in the tournament.