USA captain Claudio Reyna is facing an anxious wait to discover the severity of the hamstring injury he suffered during Tuesday's 1-0 defeat against Morocco.

The Manchester City midfielder limped out of the action after just 16 minutes and is to undergo a scan on Wednesday to determine whether he will be able to play any part in the World Cup finals.

Reyna told US Soccer's official website: "I'm going to get an MRI. It just tightened up on me. I stretched out for a ball, and just to be cautionary I came out.

"It is close to the finals, so obviously it is not the best timing. But I'm hoping I've gotten away with something very minor.

"I'm optimistically thinking that it is not going to be something long term, but tomorrow I will know better."

The injury came at a time when Reyna was confident he was approaching full fitness after battling shoulder and ankle problems earlier in the season.

The 32-year-old added: "I felt fine. The training we did last week, I had no problems and in the last six or seven weeks of my season, I've felt fine. So it is just one of those things that just happened."