TUSCALOOSA _ One assisted tackle. Half a tackle for a loss. One quarterback hurry.

One knee.

That was defensive end Damion Square's season in 2009, after working his way up and putting himself into position to be a regular pass-rusher in just his redshirt freshman year. It came to a quick and abrupt end against Florida International when he tore both the anterior cruciate ligament and meniscus on a play he still describes as "I was pass-rushing and (then) I was on the ground."

It was that quick.

Two weeks later linebacker Dont'a Hightower wound up in the training room as well after blowing out his knee against Arkansas and the two began the long arduous task of not only getting back, but being ready before expected in time for spring workouts.

"We had a lot of good times down there despite the circumstances," Square said. "He was my motivation to come in and get better every day and I was his motivation to come in and get better every day because we knew what we would have to bring to the team this year.

"It was a slow process that speeded up with the great guys we have in the training room. My knee couldn't be any better than what it is right now and every day I go out there is if I'm a hundred percent even if I'm not."

So far, Square is back in the mix as if nothing changed defensively, when it reality the opposite is true. While the revamped secondary has had injury issues and the linebacker corps has nearly as many new contributors, the defensive line has quietly gone about its business.

Sort of.

Defensive end Marcell Dareus is still waiting for a ruling by the NCAA regarding his eligibility, although at this point any potential penalty is not expected to be harsh. About the only critical thing Nick Saban has said of the junior is that he'd like him to shed a few pounds before the season starts.

"Marcell really hasn't shown a lot of signs of a guy who's not focused on the right things for what he needs to do to be a good football player individually," the coach said. "He's also been pretty selfless in trying to influence and impact (teammates), especially the guys in his group."

Sophomore end Undra Billingsley, a converted tight end who has been working behind Dareus and ahead of the Darrington Sentimore, has missed the last couple of practices after sustaining an ankle sprain, but could return Friday.

Sophomore Kerry Murphy has been lining up with the first-unit at nose tackle this week ahead of his former Hoover High School teammate Josh Chapman - who was seen with a wrapped hamstring earlier in camp. While it's raised some eyebrows, his development has also been a long time coming due to eligibility issues that required a stint at Hargrave Military Academy in Virginia to qualify.

Despite being listed as 6 foot 3, 319 pounds, Murphy's considered one of the most athletic players on the Crimson Tide -- teammates say that back flip he used to do in high school was legit -- and at minimum will almost certainly be a major part of the rotation.

"Great first step, great size, has really gotten his confidence, back," said junior center William Vlachos, the Mountain Brook product who estimated he's playing against Murphy since the seventh grade. "You know he went to Hargarve and he played some offense and stuff like that. That's a big thing with him."

So there's depth, which is the best thing to have when it comes to a defensive line, especially when all three starters have had to be replaced after making a combined 83 starts.

"I'll play wherever coach wants me to," Square said. "Pass-rusher, goal-line, whatever it takes."

He might do both, and is ahead of last fall when Square essentially forced his way on to the field with his impressive fall camp. Primarily, the converted linebacker has been lining up behind Luther Davis, the lone senior starter on the defense, with junior-college transfer Brandon Lewis probably more of an every-down reserve option.

"Damion Square done a nice job, we're pleased with what he's done and what he's doing," Saban said. "He probably has a good chance to play for us some in nickel and probably be a prepared to be a regular end. He's a good athlete, he's worked hard, he's gotten bigger and stronger."

"Rusher, he's top-notch," sophomore tight end Michael Williams said. "Him coming off the knee surgery, you can't even tell the way he comes off the edge. Run-blocking he's just as tough as any D-linemen that we have."

During the spring Square took reps with the first unit as a pass-rusher, ironically alongside Hightower. Granted, Dareus will probably be the dominant player in that situation this season, but he figures to get his snaps, and it wouldn't be surprising if the line rotation isn't expanded a bit more than what Alabama fans have recently seen.

"We have a lot of guys who can bring something to the table," Square said. "We want to be a great unit."