Two of those eyeballs will belong to a man whose job it is to test the condition of that knee.
Lungs will expand and then hold that extra air momentarily the first time Carlos Condit's forward-swinging leg moves in the direction of Georges St-Pierre's surgically repaired knee at a rapid speed.
Such a reaction can be considered expected, even fair, as St-Pierre returns to live mixed martial arts fighting at UFC 154. It is his first fight in 586 days. A torn ACL did something no fighter since Long Island's Matt Serra in 2007 could do: stop GSP.
But the true welterweight champion is back to unify the title with interim champion Condit, the very talented fighter who has sat atop another man's kingdom as if he were a principle character in "Game of Thrones."
St-Pierre went through extensive rehab, says his knee is 100 percent and he's a better-conditioned athlete because of it.
But rehabbing a torn ACL is a long and arduous process. Six months to a year is the typical period for full recovery. Many athletes say it takes a second year before they feel "right."
GSP had his doubts early on.
"When I first got back, I was sparring with guys, very lightweight people and I got tired after one round, exhausted," St-Pierre said. "I had to step out of the training because I was getting my [butt] kicked."
GSP was used to having his body do what his mind tells it to do. That's part of how he has amassed a 22-2 career record and six straight title defenses.
Even a supremely conditioned athlete such as GSP had to learn that the body must heal.
"I used to have the mentality before when I was I training that more is better, but I realized smarter is better," St-Pierre said. "Recuperation is part of the training. I realized I needed to listen to my body more."
The anterior cruciate ligament is the great equalizer among athletes. No matter how big, strong, quick or agile an athlete is, when the ligament that stabilizes the knee and helps connect the femur and tibia tears, they all fall.
"I'm a very proud person," St-Pierre said. "It was hard on my ego. I used to be the dominant guy and now I'm getting beat up by the smaller guy, not even professional level sometimes. Everybody was looking at me and I could see some people were like 'He's never going to come back the same.' "
St-Pierre is a meticulous trainer and fighter, always searching for perfection. He always says his next opponent is the toughest opponent he's ever faced. So when the 31-year-old champion from Montreal winds up on the losing end of a sparring round in a gym against someone whose name may never be known outside of his home and gym, crisis mode begins. Time fixes that, though, as GSP has learned.
"When you haven't done this for a long time, you lose your efficiency and that's what happened to me. I got very tired very fast," St-Pierre said. "You need to go through that. You need a force of character to push through it."