The U.S. is uncertain of Jozy Altidore's availability for the Copa America Centenario following yet another hamstring injury as Jurgen Klinsmann named a 22-man squad for training camp this week in Miami.
The team also will be without a half-dozen foreign-based players for Sunday's exhibition game at Puerto Rico because of club commitments.
Altidore, who hasn't scored for Toronto in Major League Soccer this season, got hurt on Saturday while taking a penalty kick against Vancouver that was saved. The U.S. team was awaiting results of an MRI.
Altidore 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.