Green Bay Packers coach Mike McCarthy says cornerback Al Harris has a "serious" spleen injury that requires a cautious approach, but he's not yet ruling out one of the team's top defensive players for the rest of the season.

"I'm hopeful that he'll be back," McCarthy said Wednesday. "The timeframe just hasn't been established."

Harris was injured in the first quarter of the Packers' loss to the Dallas Cowboys on Sunday night. The injury is believed to be a ruptured spleen, which sidelined then-Tampa Bay quarterback Chris Simms for the rest of the season in 2006.