Baltimore Ravens linebacker Ray Lewis underwent surgery to repair a torn hamstring yesterday, officially ending a season in which he was limited to just six games and adding another disappointment to an already reeling team. Lewis is expected to be placed on injured reserve for only the second time in his 10-year career in the next week.

Lewis, a two-time NFL defensive player of the year, originally injured his right hamstring during the Ravens' 10-6 loss at Chicago on Oct. 23. He has not played or practiced since, though he resumed running in late November.

The Ravens (4-8) were hopeful that he would be able to practice last week in preparation for the Houston game, but he missed the 16-15 win over the Texans. After consulting with a specialist in Miami over the weekend, Lewis opted to have surgery in Florida.

"It's the right thing to do. It gives him the maximum rehab time," Coach Brian Billick told reporters in Owings Mills, Md.

"There were multiple opinions. He sought them all, we sought them all, and it was great that we were able to come to some resolution. It was the right thing to do, and I'm sure he's very comfortable with it."

Billick said that he did not know the timeframe for Lewis's rehabilitation.

In Lewis's absence, the Ravens moved veteran Tommy Polley to middle linebacker and inserted Bart Scott at outside linebacker. Polley leads the team with 93 tackles (according to coaches' video review), and Scott, who joined the Ravens in 2002 as an undrafted free agent, has been a pleasant surprise with 41/2 sacks.

Still, Baltimore has missed Lewis's presence in the middle. In three of the past four weeks, the Ravens have given up 100 yards to an opposing running back -- something they rarely do when Lewis, who missed 11 games in 2002 with an injured shoulder, is around. The Ravens travel to Denver (9-3) this weekend.

"Oh, it's huge, it's huge, but you gain some things when you lose a player of that caliber, because other people have to step up," Billick said.

"We did in 2002; we have this year. We'd prefer not to go through it, but we'll focus on the things we've been able to do with Ray Lewis not there, and the people that have stood up. We have a much better idea of what their abilities are."