McGahee was scheduled to have surgery Monday at Doctors Hospital in Coral Gables, Fla., to repair a knee that's been bothering him since shortly after reporting to training camp.
It's the same hospital that performed several reconstructive surgeries on the Pro Bowl alternate's left knee after he shredded nearly every major ligament during the Fiesta Bowl five years ago while playing for the University of Miami.
Team officials consider this to be a minor procedure.
"We're going to go in there and scope and clean it up just to make sure he's going to ready to play opening day and make sure we know exactly what's going on in there," Ravens coach John Herbage said.
Traditionally, it takes two to four weeks to recover from a standard arthroscopic knee surgery. In the case of McGahee, who didn't report to camp in optimum condition, it's likely going to come down to how much swelling there is and how diligently he works at his rehabilitation.
The Ravens open the season Sept. 7 against Cincinnati at M&T Bank Stadium.
Harbaugh acknowledged that there are potential scenarios where McGahee may be unavailable for that game, which would open the door for rookie Ray Rice to start.
"There's always a possibility," Harbaugh said. "You never say never on those things, but we're confidence without the scope he would've been ready. We just feel like this is kind of a cautionary procedure to make sure we're right."
Signed to a $40.12 million contract last year after being acquired in a trade from the Buffalo Bills, McGahee rushed for 1,207 yards and seven touchdowns during his first season in Baltimore.
He was held out of the Ravens' preseason opener against the New England Patriots and hasn't practiced on a regular basis in two weeks.
"We continue to move on," wide receiver Derrick Mason said. "Willis is a big part of our offense, but, right now, it's preseason. We expect him back for the first game."
Now, the Ravens are going forward with Rice as the starter. Cory Ross, Allen Patrick and Alex Haynes are working behind the shifty second-round draft pick from Rutgers.
Rice has been impressive in camp, but didn't produce big numbers against the Patriots with six carries for a dozen yards and four receptions for 17 yards.
"Ray has been doing a great job," Mason said. "I'm really impressed by what Rice has been able to do in a short period of time."
None of the Ravens' backup runners has much experience, though, and the personnel department is already fielding calls from free agent running backs' agents. However, the Ravens don't seem inclined to sign anyone immediately.
Najeh Davenport, Marcel Shipp, Anthony Thomas, Verron Haynes, Shaun Alexander, Travis Henry and Mike Bell are among the available free agents, but the Ravens are most likely to just go with Rice if McGahee is unavailable. The Ravens didn't re-sign Musa Smith during the offseason and he signed with the New York Jets.
"No matter what is happening on our depth chart with injuries, we're working hard to overcome it," center Jason Brown said.
The Ravens combined for just 35 rushing yards on 21 carries for a 1.7 average per carry against New England as the backs didn't break many tackles and the linemen didn't hold their blocks quite long enough for Rice to scoot upfield.
"With Willis out, we just come in with the same mentality that we're all competing for a job," said Patrick, a seventh-round pick from Oklahoma who gained nine yards on two carries last week. "Everybody is going hard, and we feel like it's a pretty close race. I'm just trying to improve, and, hopefully, everything is starting to come together for me."
Aaron Wilson covers the Baltimore Ravens for the Carroll County Times and the Annapolis Capital..
McGahee undergoes knee surgery
Ravens Insider Top Stories
Fantasy Football Funeral: Au Revoir ForsettIt's time for a Fantasy Funeral...
Scout FantasyWednesday at 11:23 AM
Week 7: Snaps Impact & Target AnalysisEvery week, Fantasy Football Expert Jack Delaney will closely examine the snap counts, usage numbers and target totals for players across the league to better prepare you for the…
Scout FantasyTuesday at 10:49 AM
Week 6: Wide Receiver Corps To WatchFantasy Football Expert Mark Morales-Smith looks at a few wide receiver groups to watch heading into Week 6!
Week 5: West is Best For RavensSenior Fantasy Football Expert Shawn Childs looks at each position player on the Baltimore Ravens to determine whether they are worthy of a spot on your Week 5 DraftKings lineup!