US striker Patrick Agyemang has suffered an Achilles tendon injury that will keep him out of the World Cup, his English club Derby County said on Tuesday.
The 25-year-old was injured in the first half of Derby's 2-0 win over Stoke City in the Championship (second tier) on Monday and was taken off on a stretcher.
"The club will provide Patrick with the highest level of medical care and rehabilitation throughout his recovery," the club said in a statement.
"As a result of this injury, Patrick will unfortunately miss this summer's FIFA World Cup. At this stage it would be wrong to put a timeline on his recovery."
Agyemang has scored six goals in 14 internationals since making his US debut last year. He played in both the team's friendlies during the March international window.
US coach Mauricio Pochettino must name his World Cup squad by 30 May. The US, co-hosting the tournament with Canada and Mexico, will face Paraguay, Australia and Turkey in Group D.
The World Cup starts on 11 June.