TEMPE, Ariz. -- The toughness of co-defensive coordinator Tom McMahon has been an inspiration to Colorado.

Coach Gary Barnett calls McMahon "the toughest dude I know," and it's hard to argue.

McMahon, who had a cancerous lung removed last year and then was felled by a serious infection in November, is back coaching on a full-time basis.

McMahon's determination to keep working despite the ravages of his disease has been inspiring to his players and fellow coaches.

A player with an ankle injury has a difficult time complaining about his malady in the presence of McMahon.

"Any time I'm beat up," defensive tackle Justin Bannan said, "I just look over at coach McMahon and I'm like, `Stop being such a wimp."'

Safety Robbie Robinson said McMahon "got a lung removed and was back about a week later. To go through what he's gone through and still be able to come out here and help us get better, that's a pretty amazing thing.

"We really don't have anything to complain about. He's been just a great inspiration to us."

The 53-year-old McMahon, who also coaches the Buffs' secondary, missed three games last season following surgery in September.

After coughing up blood, he went through a battery of tests that showed a malignant tumor the size of a tangerine in his right lung, which doctors termed inoperable because of its size.

Radiation and chemotherapy helped shrink it, and his lung and lymph nodes were removed Sept. 13.

"They felt they got most of the cancer," McMahon said Saturday as his Buffaloes continued preparations for Tuesday's Tostitos Fiesta Bowl against Oregon.

McMahon returned to work with no serious setbacks for about 13 months. But, immediately after a home game this season against Missouri on Nov. 3, he was hospitalized for treatment of flu-like symptoms.

It turned out to be an infection in the cavity where his lung had been removed. Aggressive treatment with antibiotics finally worked, but McMahon missed games against Iowa State and Nebraska.

"It's really hard to sit in front of a television set and watch the team play, especially against Nebraska," he said. "You're gnawing at the bit to come back, but you know you don't want to come back too soon."

McMahon managed to accompany the Buffs to Texas for the Big 12 title game and worked the entire game.

"That was a thrill for me," he said. "It was a matter of being able to stand on my feet for that long, being able to concentrate and being able to contribute. I didn't want to come back until I felt I could contribute."

When the Buffs earned a bowl bid and began practices in early December, a gaunt McMahon was with them, offering his usual sharp criticism as he coached in the 30-degree temperatures.

Asked if McMahon was the sort of person he would want with him in a street fight, Barnett chuckled, "He needs to put on a little weight. I don't know if he can whip anybody right now.

"But he's the guy I want with our players."

Bannan agreed, saying, "I don't think I've ever known a better man or a tougher man in my life."

McMahon said Saturday he feels "a whole lot better. Now I'm starting to get my energy back. I'm at the point where I feel good more than I don't feel good.

"I'm doing everything. I'm able to go to meetings, to make it through practices and evaluate practices afterward, and do some of the game-planning. I'm really back as full as I've ever been."

He knows his fight is not over.

"We don't talk about long-term prospects," he said. "We just talk about how to win this day."

Working in the job he loves has been therapeutic both for McMahon and the team.

"This is tremendous," he said. "You can't put a value on doing the thing you love to do the most.

"I get tired every now and then. I could sit back and think, Well, what's next? But you don't have time to be concerned about that because there's so much else going on. I'm trying to figure out how we can win one more game."

His illness also has taught him not to take things for granted.

"I really enjoy going out and facing the sun and having it shine on me," he said. "I think more about my family. Those things are enjoyable.

"I used to get overwhelmed with things that weren't done right. Now, I don't. I just keep working, do the best I can and keep moving."