Alex Morgan is a big unknown for the US heading into the Women's World Cup

Heading into the Women's World Cup, the health of U.S. women's national team forward Alex Morgan has become one of the team's biggest question marks.

Morgan hasn't played for the U.S. or her club team, Portland Thorns FC, since suffering a bone bruise in her left knee in early April. What was originally classified as a "minor injury" has forced Morgan to miss the USWNT's past three friendlies.

U.S. coach Jill Ellis, however, does not believe the situation is as dire as Morgan's absence suggests. With Morgan returning to practice Wednesday, Ellis said she's been "very pleased with the progress" she has made. The AP's Anne M. Peterson wrote that Morgan "appeared agile" during the brief portion of the practice open to the media.

While it appears that Morgan will, in fact, play in the group stage for the U.S., Ellis told Sports Illustrated's Grant Wahl that Morgan will most likely come off the bench in order to build up her endurance and avoid any additional injuries:

"In terms of Alex, we're building her. ...Realistically, she's been off for a while. So in terms of minutes, that's something I think we're going to have to build through the early games to be ready. We don't want to blow her up too early in terms of physically being ready."

Fellow forward Abby Wambach said that Morgan's injury could actually be an advantage for the U.S. Wambach believes those seven weeks of time off could result in a fully rested Morgan becoming "one of the U.S. national team's greatest assets" if they advance into the knockout stages.

However, if Morgan doesn't get fully fit, it will put even more pressure on the Wambach, the team's most experienced forward.

Morgan however, doesn't believe that will happen. During media day last Wednesday, Morgan said her knee is doing well, and she will be ready for the U.S.'s opener against Australia:

"I've been doing a lot better and I'm still day-to-day. Once June 8 comes, there's no question in my mind that my knee will not be bothering me. I'll be 100%."

The U.S. certainly hopes that will be the case. Here's the full U.S. team schedule for group play:

• Austrlia (June 8, 8 p.m. eastern, Fox Sports 1)
• Sweden (June 12, 8 p.m. eastern, Fox)
• Nigeria (June 16, 8 p.m. eastern, Fox)