Jozy Altidore has provided the United States with an injury scare after suffering a sprained ankle in training.
The striker was hurt during a training session on Wednesday and was unable to take part in further practice with his team-mates on Thursday.
The US Soccer Federation confirmed Altidore's injury with a short statement posted on its website, citing the injury as a mild ankle sprain.
"Jozy Altidore sat out training today after incurring a mild right ankle sprain during Wednesday's practice," the statement read.
"Altidore's status is considered day-to-day, and he will undergo a fitness test Friday to determine his availability for the June 5 friendly against Australia."
The 20-year-old is expected to lead the USA line for their opening game of the tournament against England in Rustenburg on 12th June providing he shakes off the ankle complaint.
Altidore spent the past season on loan at Hull City from Villarreal, but scored just once in 28 Premier League appearances and was sent off in his final outing against Sunderland.