A three-time Pro Bowl cornerback, McAlister missed the past two games because of the knee injury after getting benched Oct. 19 at Miami.
McAlister, 31, saw specialists in Florida and Canada before informing Harbaugh yesterday about his decision. Harbaugh said the operation would repair cartilage and posterior cruciate ligament damage.
"He expressed to me that he felt like it was in his best interest," Harbaugh said. "The knee is a problem. It's a problem because of the position he plays. It just wears the knee down. So, he has to get that corrected."
Cornerback DeAngelo Hall is no longer a possible replacement. The NFL Network reported yesterday that Hall, who had been waived by the Oakland Raiders on Wednesday, had reached a one-year agreement with the Washington Redskins.
Before the network's report, Harbaugh said the team had "preliminary" discussions with Hall, who turns 25 on Nov. 19, a two-time Pro Bowl player for the Atlanta Falcons before being traded to the Raiders this offseason.
"We got some really good corners," Harbaugh said. "We don't need a top corner. We need another good football player."
McAlister made three interceptions in the first four games of the season. But he was burned twice for touchdowns by the Indianapolis Colts' Marvin Harrison on Oct. 12 and was benched a week later in Miami.
After Harbaugh and McAlister said he was not injured, McAlister appeared on the injury report two weeks ago with a knee injury and subsequently missed the next two games.
The reaction among McAlister's teammates was subdued.
"Chris is one of our best players. You definitely don't want to lose a guy like that," cornerback Fabian Washington said. "I feel like I'm going to have to step up and play big because those are some big shoes to fill. I've got to pretty much just do what I've been doing, but just raise the bar."
Some of McAlister's teammates said they admired his determination to play through the problematic knee.
"He didn't even have to go out there and try to participate with that bad knee," cornerback Corey Ivy said. "Playing the position that he plays, you definitely need your legs. You need two healthy ones at that. So he hung in there and stuck it out as long as he could and decided to have the surgery, which is probably the best thing for him and his career."
It's unknown whether McAlister has played his final game for the Ravens. He is one of the highest-paid players on the team and is scheduled to earn $8 million in the final two years of his seven-year deal (2009 and 2010).
In other injury news, the Ravens could place safety Dawan Landry (neck) on injured reserve as early as Monday. Landry would become the third defensive starter to be put on IR, joining McAlister and nose tackle Kelly Gregg (knee).
"I wouldn't say it's optimistic right now," Harbaugh said of Landry, "but we're still trying to hold out hope."
Notes:: Linebacker Bart Scott and cornerback Samari Rolle are listed as questionable for tomorrow's game against the Houston Texans after being limited in practice for the third consecutive day. Scott is dealing with a chest injury, but he hasn't missed a game since Jan. 2, 2005. Rolle has missed the past six games after undergoing neck surgery. Tight end Daniel Wilcox missed practice for the second straight day because of illness and a left thigh injury, and he is doubtful. A number of players - running backs Willis McGahee (ankle) and Ray Rice (chest), fullback Le'Ron McClain (ankle), offensive tackles Adam Terry (sprained right knee) and Jared Gaither (stinger), and defensive tackle Brandon McKinney (shoulder) - participated fully in practice after being limited the previous two days. ... For the Texans, starting defensive tackle Amobi Okoye missed his third straight day of practice and is listed as doubtful with an ankle injury. Linebacker DeMeco Ryans (shoulder), wide receiver Kevin Walter (back) and running back Ahman Green (thigh) practiced fully and are probable. ... Linebacker Jarret Johnson's only career interception and 6-yard return for a touchdown came against quarterback Sage Rosenfels in a 30-23 win over the Miami Dolphins on Jan. 2, 2005. Rosenfels will start for the Texans. "He tried to run a screen and tried to throw it over my head," Johnson recalled. "I jumped up and tipped it and caught it and ran it. Hopefully, he'll throw me another one." ... Because of Wilcox's uncertain status, Terry could get a few snaps at tight end. "Well, he lines up at the end of the line, so he looks comfortable," Harbaugh said. "He's had some pass-receiving experience, he tells us. So we worked on that, too."
Baltimore Sun reporter Edward Lee contributed to this article.
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