BRIDGEVIEW, Ill. -- Alex Morgan reinjured her left ankle, just four months after returning to action following a long layoff.
The American star forward got hurt in the 37th minute of Friday night's 5-0 win over Guatemala in the CONCACAF Women's Championship.
Morgan was to have a scan to determine the extent of the injury.
"She's pretty optimistic, which is a good sign," coach Jill Ellis said. "She's a tremendous player. It would be a loss if we didn't have her."
Morgan, who has 49 goals in 77 international appearances, first hurt the ankle during training late last October, then played against Brazil on Nov. 10. She was sidelined until returning to action on June 7 with her club, the Portland Thorns of the National Women's Soccer League.
She reinjured the ankle in a collision with Guatemala defender Londy Barrios. Morgan tried to put weight on the ankle on the sidelines but then was replaced by Christen Press in the 42nd minute.
Tobin Heath scored twice, and Carli Lloyd, Whitney Engen and Megan Rapinoe had one goal each as the U.S. improved to 2-0 in the group stage of the tournament, which serves as qualifying for next year's World Cup.
Goalkeeper Hope Solo got her 75th shutout and didn't need to make a single save as the Americans outshot Guatemala 21-0.
The U.S. had started the tournament with an unimpressive 1-0 win over Trinidad and Tobago.
"Things opened up, and we converted our chances this time," Rapinoe said.
Heath scored the first goal from 4 yards with a sliding, right-footed shot in the seventh minute off a short pass from Sydney Leroux, beating goalkeeper Alicia Navas.
"The first half, we were waiting to see if the ball fell in place rather than going after it," Lloyd said.
Lloyd doubled the lead in the 46th off an assist from Leroux, and Heath made it 3-0 in the 57th. Engen scored in the 58th and Rapinoe in the 66th.
Seeking its third World Cup title but first since 1999, the U.S. leads Group A with six points, followed by Haiti and Trinidad and Tobago (both 1-1) with three each. Guatemala (0-2) is last.
The top two teams in each of two groups advance to the semifinals Oct. 24 in Chester, Pennsylvania. The top three teams qualify for the World Cup in Canada, and the loser of the third-place game meets a South American nation in a playoff for another berth.
Alex Morgan reinjures ankle as U.S. shuts out Guatemala in qualifier