GREEN BAY, Wis. -- Cornerback Al Harris has a "serious" spleen injury that requires a cautious approach, but he hasn't been ruled out for the rest of the season, Packers coach Mike McCarthy said Wednesday.
"I'm hopeful he'll be back," McCarthy said. "The time frame just hasn't been established."
Harris, one of the Packers' top defensive players, was injured in the first quarter of Green Bay's loss to the Dallas Cowboys on Sunday night.
"It's a serious injury," McCarthy said. "I think that's obvious to everybody. And really, as we move forward, it's a different type of injury. And we will take a cautious approach, and everything we'll do will be in his best interests."
Harris' agent, Jack Bechta, said his client's spleen is lacerated and a CT scan revealed some damage and bleeding. A re-evaluation will be scheduled in a couple of weeks, said Bechta, who added Harris cannot resume football activity until doctors determine the spleen is healing. Harris will not play in Sunday's game at Tampa Bay.
McCarthy said Harris has sought at least three medical opinions this week and there's a "good chance" he can avoid surgery.
"If Al was standing here, he'd tell you he'd want to play this week," McCarthy said. "That's kind of how he feels."
Harris left Sunday night's game in the first quarter after he collided with Packers linebacker A.J. Hawk. Harris returned two plays later.
But he left again and did not return after tackling Cowboys running back Marion Barber. Harris went to the locker room in the second quarter with what team officials described as cramping. McCarthy said after the game that Harris had blood in his urine and was not allowed to return by the team's medical staff.
Harris could be facing a road similar to Chris Simms. Simms ruptured his spleen in a game against the Carolina Panthers in 2006 and had an emergency procedure to have it removed. He missed the rest of the season and returned in 2007, but was inactive for the first five games before being placed on injured reserve.
The Buccaneers cut Simms in August, and he signed with Tennessee this month. Simms has yet to play in any of the Titans' three games.
Losing Harris for any extended time will be a difficult blow to the Packers' defense. Harris, who specializes in the aggressive style of bump-and-run coverage favored by Packers coaches, went to his first Pro Bowl last season.
Despite both being over the age of 30, he and Charles Woodson form one of the NFL's most formidable cornerback tandems. Woodson was effective against Cowboys receiver Terrell Owens on Sunday, but the Packers had a hard time containing the rest of the Cowboys without Harris on the field.
"Any time you lose guys, it's hard, but you expect other guys to step up," Packers defensive coordinator Bob Sanders said after Sunday's game. "But certainly losing Al, a guy of that caliber, that hurts. Anytime you lose a guy like that, it's not good."
Harris' starting spot will be taken by second-year player Tramon Williams.
Information from ESPN.com senior NFL writer John Clayton and The Associated Press was used in this report.