NASHVILLE, Tennessee, May 24 (Reuters) - U.S. captain Claudio Reyna did not suffer any muscle damage when he limped off in the 1-0 defeat against Morocco on Tuesday.
It was feared the Manchester City midfielder had pulled his hamstring when he had to come off after only 15 minutes when he over-extended his leg trying to intercept a pass.
However, a scan on Wednesday showed there was no serious damage and U.S. officials said the prognosis was very good.
'There was no damage but of course it's not 24 hours after the injury,' said U.S. assistant coach Glen Mayericki.
'It still needs to quieten down. There are no alarm bells going off but he will be out for an extended time.'
There is no timeframe on when Reyna will return to training and team staff will base everything on his pain threshold.
'It's very good news,' Reyna told Reuters at the U.S. training camp. 'I'm a lot happier now than I was last night.
'I'm still not sure when I'm coming back but I'm not going to rush it. I don't want to come back too soon.'
Reyna, who missed the first match of the 2002 World Cup with a quadriceps strain, is sidelined for Friday's friendly against Venezuela. The U.S. already planned to make wholesale changes.
Midfielder Pablo Mastroeni also suffered a knock on his knee and did not train on Wednesday as a precaution.
The Morocco match was the first time Reyna had played for the U.S. since September 2005 when they beat Mexico 2-0 to qualify for the World Cup finals.
He broke his right ankle in December and missed eight weeks after surgery. Three games into his comeback Reyna injured his shoulder against Wigan Athletic in March and was out for nearly four weeks.
Reyna has scored eight goals in 109 appearances for the U.S. and also appeared in the 1994 and 1998 finals.
The U.S. face Italy, Ghana and the Czech Republic in Group E at the World Cup, which starts on June 9 in Germany. The U.S. kick off their campaign against the Czechs on June 12.