Houston Texans defensive end J.J. Watt had a number of injuries last season, but he has revealed a staph infection was the most dangerous one.
The three-time Defensive Player of the Year has played only three times in 2016 after multiple surgeries to fix muscular tears and a twice herniated disc in his spine.
However, the 27-year-old has revealed how his career was briefly put under threat by illness last year.
"One Friday night last season, I noticed some weird bumps on my knee. I thought it was a rash, so I went and asked our trainer if he had any cream," Watt wrote for The Players' Tribune.
"He looked at my knee and said, 'That looks really bad. We have to get you to the hospital right now.'
"I thought he was joking at first. But then I could see in his face that he was serious and actually a bit panicked.
"As it turned out, he saved me in a big way.
"At the hospital, they immediately put me on three hours of the strongest antibiotic IVs. I went straight from the hospital to the team plane and we flew to Jacksonville. Once we landed, there were two more hours of antibiotics that night and two more the next morning before the game.
"The medicine had completely drained me, but I played -- and we won.
"I remember walking into the locker room after the game and just collapsing on the training table. My body was completely shot, with nothing left to give.
"As the trainers hooked me up to an IV, one of the guys walking past joked, 'You alive?' Later that day on the flight back to Houston, one of the team doctors told me that if our trainer hadn't recognised the problem so quickly, I could have lost my leg."
Watt's infection was previously unknown, and as he notes, he played the Week 6 game against the Jacksonville Jaguars after undergoing treatment. He finished that game with just two tackles, which tied for a season low, and played 98 per cent of the defensive snaps.
In the article, Watt also admitted he briefly thought about retirement after all of the surgeries.
"Yes, over the last year, I've been through some dark times, and my body was beat up more than most people probably realise," he added.
"But I've learned that a life without adversity is a boring life to live. I've experienced the highs, and I've experienced the lows, and both are better than living in the middle.
"The kid in me is back.
"Am I done? Hell no. I'm just getting started."