When Gene McCaskill felt the pop, he nearly threw up.
The pop happened while the Kentucky wide receiver was in the process of doing rehab for his second knee surgery.
"When that last one happened, I didn't know what to think," McCaskill said Sunday. "A lot of stuff runs through your head like, should I even keep playing?"
Late in August of last year, McCaskill went through difficult reconstruction of a torn anterior cruciate ligament.
Then in January, he had to have arthroscopic surgery on that same knee.
After doctors OK'd him to start running again, that's when he felt the pop. This time it was a partially torn meniscus in that same knee.
"I've had a lot of downs since my first surgery," the Chester, S.C., native said. "It's been rough. Just rough. There's no other way to describe it."
As he went through rehab again, McCaskill pondered giving up football, something he's loved since he was a kid.
"It definitely runs through your head," he said of quitting, which might have been easier than the rehab he went through twice a day, seven days a week.
There were points during that grueling process that McCaskill worried about another pop.
"The hardest part was in the summer time, just trusting," the knee, he said. "Cutting on it and thinking it's going to give out. After three surgeries, you wonder if it's going to give out again."
But at some point this summer — McCaskill doesn't exactly remember when — the 6-foot junior wide receiver decided that he couldn't think about the knee and potential pops anymore.
"It got to the point that I just had to put it away," he said. "I decided I was going to cut as hard I can and if it goes, then it goes. That's the mind-set you've got to have coming back from surgery.
"I'm doing my cuts now even harder now than I was before."
McCaskill is a player you can't help but root for, junior quarterback Morgan Newton said last week.
"Gene's one of those guys that's one of your favorite people every time he steps in a room," Newton said. "He's always on everybody's side. He works really hard and wants to be successful.
"He's had his ups and downs, and we're looking forward to his ups."
His highest up at UK came in his freshman season when he made three catches for 64 yards in the Autozone Liberty Bowl, including a career-best 48 yarder.
Assistant coach Tee Martin said until McCaskill went down, he didn't realize just how versatile a player UK was missing.
"He played all three positions and it forced me to put (La'Rod King) into positions that weren't in his comfort zone, but he did a good job," Martin said.
The wide receivers coach said McCaskill could be an "X-factor" for UK this season.
"With Gene coming back, we get to do some things we weren't able to do," Martin said. "He seems like he's ready to come back, which will be good for our young guys because he's somebody who's made some plays for us."
It's also good for the young guys because McCaskill said he learned a lot about his position during his time away and he's eager to help teach UK's talented but untested crop of newcomers.
"Sitting out last year helped me so much as far as watching the game and getting mental reps," he said. "Just being in the film room and coming to the games on Saturday was really helpful."
Martin made it a point to keep McCaskill in the loop.
Meetings, walk-throughs, film study, McCaskill has been around for all of those events.
"I feel good about him being able to come in and dust off the rust a little bit because of that," Martin said.
There were times last season when Martin would literally grab McCaskill out of the training room and have him come watch the new play the coaches just put in.
It kept McCaskill hungry to keep doing his rehab so he could get back to playing on Saturdays.
"It's been a rough road, but hopefully the knee is coming back to 100 percent," McCaskill said. "I'm excited to get back on the field."