Alex Morgan, a star on the United States women's national team , has been diagnosed with a mild MCL sprain in her left knee.

The Portland Thorns revealed Thursday's MRI results, and said that Morgan will begin rehabilitation immediately at Providence Sports Care Center at JELD-WEN Field and with Portland Timbers medical personnel. She is expected to miss between 2-4 weeks.

Morgan sustained her knee sprain Wednesday night after colliding with Boston Breakers' Jazmyne Avant in the 10th minute of the Portland Thorns' 2-1 defeat in the National Women's Soccer League. Morgan was taken to the dressing room but returned and watched the remainder of the game from the sideline with a large brace on her left knee.

"It's a relief that there is no significant damage to my knee. I will do everything in my power between now and Aug. 24 in order to be available for the playoffs and to win the championship," Morgan said in a statement released by the Thorns.

The 24-year-old striker is one of the national team's brightest stars, and is expected to play a critical role in the upcoming 2015 Women's World Cup .

Despite losing Morgan and the game, Portland qualified for the inaugural NWSL playoffs. The Thorns join FC Kansas City, Western New York and Sky Blue FC in the postseason. Should Morgan be unavailable for the playoffs, it would be an enormous blow. Morgam is Portland's leading scorer, with nine goals in 18 games plus four assists.

The 2012 Olympic gold winner remains upbeat and thanked the club's medical staff:

Last night was rough but thanks to amazing Docs/trainers I was able to get immediate care. On the road to recovery! http://t.co/lEZAWgeBIT

-- Alex Morgan (@alexmorgan13) August 8, 2013