-- This is not how Dan Cody envisioned his career with the Baltimore Ravens beginning. The rookie linebacker fell, clutching his right knee, during the first practice of training camp on Monday. Cody, the Ravens' second-round draft pick (53rd overall), ended the day on crutches.

An MRI exam revealed a second- to third-degree sprain of the anterior cruciate ligament in his right knee. A third-degree sprain is the most severe and involves a complete tear of the ligament; such an injury generally results in season-ending surgery.

Cody will be evaluated later in camp, and he will undergo another MRI once the swelling in his knee goes down. He will not practice until he is re-examined, and a Ravens spokesman said he could not provide an estimate on when that will be.

"If you're going to have an injury, [the first day is] the day to get it. Then it gives you time to heal," defensive coordinator Rex Ryan said. "It's really unfortunate, but that's what happens in this game. Hopefully everything will work out where he's back with us shortly, and we'll just move on."

Cody played primarily defensive end at Oklahoma but was expected to transition to outside linebacker with Baltimore. The Ravens like Cody's tenacity and were planning to use him as a pass rusher. He was also expected to back up strong-side linebacker Adalius Thomas.

"A lot was going to be expected of him," Ryan said of Cody. "If he's ready to go, it takes time. He'll just be getting mental reps instead of the physical reps."

Roderick Green, a fifth-round pick in 2004, stepped in for Cody in passing situations during the afternoon session.

Cody was injured during the second hour of the morning practice, a full-pad, full-contact workout. He remained on the ground for several minutes as the Ravens' medical staff attended to him. He was helped off the field and was on crutches when he returned to the team hotel later in the afternoon.

"It was a freaky deal. I planted to go one direction, and it just rolled over a bit," Cody said. "I'm doing pretty good. It's kind of a matter of rehabilitating and getting back to playing shape."

The Ravens were hit with several injuries last season, starting with center Mike Flynn's fractured collarbone in training camp. Tackle Jonathan Ogden, tight end Todd Heap, running back Jamal Lewis and cornerback Deion Sanders all missed significant time during the regular season with injuries.

"When you put players on a field, things happen," Coach Brian Billick said following the morning practice. "You've got to be prepared for that."

Ravens Notes: Wide receiver Mark Clayton, the 22nd overall pick in the draft, missed the first day of practice because he has yet to sign a contract.

"Mark's probably sitting down in my basement now, eating potato chips," quarterback Kyle Boller joked about the rookie, who spent part of the offseason living at Boller's house. "Nah, he wants to be here. I talked to him yesterday a little about it. I was in the same situation [in 2003]. There's a business side to it, and I just hope he can be here as soon as possible, and they can work it out, which I feel confident they will."

A message left for Ben Dogra, Clayton's agent, was not returned. . . .

Linebacker Ray Lewis is known for his intense offseason training regimen. But he made a change this year, taking two months off after the season to rest his body. He said he came to camp weighing 260 pounds, up from his listed weight of 245.

"I can play with my weight either way," said Lewis, who turned 30 in May. "My strength right now is that my body adapts so quickly because of my rest. I've never felt this strong in my life." . . .

Billick said the Ravens will move practice to their training facility in Owings Mills if the heat and humidity become unbearable.

"There comes a point when it's just not prudent; too many bad things can happen," Billick said. "We have a plan to modify it if it gets that bad."

Ravens trainer Mark Smith works on second-round draft pick Dan Cody, who sprained the anterior cruciate ligament in his right knee.