NASHVILLE, Tenn. -- Less than three weeks before the World Cup, the U.S. soccer team opened its final warmup series with a key injury and a loss.

U.S. captain Claudio Reyna strained a hamstring early in Tuesday's 1-0 defeat against Morocco, which got a 90th-minute goal from Mohamed Madihi after defender Steve Cherundolo lost the ball to Bouchaib El Moubarki.

"It's close to the games. Obviously not the best timing," Reyna said, "but I hope I've gotten away with something very minor. That's what we're optimistically thinking. I don't think it's going to be long-term, but again, tomorrow I'll know better once it calms down."

Reyna was injured about 11 minutes in when he tried to intercept a pass. Four years ago, he missed the opening 3-2 win over Portugal with a strained right quadriceps, then returned and was stellar for most of the final four games as the Americans advanced to the quarterfinals in their best showing since 1930.

The 32-year-old midfielder is among only seven players in this year's tournament appearing on a World Cup roster for the fourth time. In 1994, he missed the entire tournament with a right hamstring injury.

Four years ago, the warmup games proved costly for the United States. Midfielder Chris Armas tore an anterior cruciate ligament against Uruguay and his likely replacement, Greg Vanney, injured a knee four days later against Jamaica. That created an opening for Cherundolo, who was added to the roster.

As for this game, the fifth-ranked Americans looked shaky against the No. 36 Atlas Lions. Following a U.S. free kick, Moubarki stripped the ball from Cherundolo and sent it to Madihi, who was wide open and easily put the ball over goalkeeper Kasey Keller.

"Defensively I was very happy for 90 minutes. Unfortunately we make a mistake at the end," Keller said. "But I'm also disappointed after the mistake we didn't have guys chasing back. Things like that cost games."

Cherundolo could have put the ball out of bounds.

"It's definitely a mistake," he said.

The Americans outshot Morocco 13-5, but they generated only a few good scoring chances.

"We weren't sharp. I think we're a little bit leg-weary. We're a little bit overtrained at this point," U.S. coach Bruce Arena said. "We didn't do a good job creating chances."