It's not just about taking one last crack at beating Michael Phelps. For Serbian swimmer Milorad Cavic, the London Olympics represent a chance to prove all his doubters wrong.
All the doctors who told him that back surgery would end his career. The friends and family members, too, who begged him to reconsider before having a herniated disk repaired in July 2010.
"I'm making history and defying the odds, and that means a lot to me," Cavic said in an interview with The Associated Press. "Every doctor told me that I would never be at this level again, and here I am, I'm doing it, and I think that's testament that a little bit of human will is greater sometimes even than science."
Cavic, of course, was the closest challenger to Phelps' record eight gold medals at the 2008 Beijing Games, losing the 100-meter butterfly by such a slim margin that the sport's governing body had to review the race down to the thousandth of a second.
The California-born Serb then lost to Phelps again in a much-hyped rematch at the 2009 world championships in Rome, despite wearing an allegedly superior swimsuit.
As if those races weren't enough to erode Cavic's will, the pain in his back grew so severe during the first months of 2010 that he often needed help getting out of bed in the morning.
He also couldn't tie his own shoes, or dry his legs off after swimming or showering.
Surgery became his only option, followed by five months of recovery without any training.
Exactly a year after the surgery, in the first big meet of his comeback, Cavic failed to advance from morning heats in both of his events at the worlds in Shanghai. Forget facing Phelps again — he couldn't even make it to the semifinals.
Over the past year, however, Cavic has slowly regained his form.
"I'm doing constant treatment. I cannot go without two massages per week. It's just an uncomfortable feeling and after a hard workout I can't go without a massage just to recover," Cavic said. "But I'm in a position to work in a way that I wasn't able to work in the past. That's definitely a huge advantage. I'm not sorry I did that operation.
"Through the last Olympics I would do three workouts and then maybe skip one or two. I didn't have any kind of real continuity in my training because my back would not allow it," Cavic added. "Thankfully that's in the past now."
Cavic showed his return to form by winning the 100 fly at the European Championships in Debrecen, Hungary, in May.
"I've already been European champion before, but I've done nothing in two years and it's not so much the title that's important to me, it's the proof and the hope that even after such a surgery I had it's possible to come back," Cavic said. "Even in the face of all my critics — my family, my friends and even doctors who said I would never come back."
Earlier this year, Cavic made another risky decision, changing coaches just four months before the Olympics.
Cavic left Italian coach Andrea Di Nino and went back to the United States to work with Mike Bottom, the coach he swam for at the University of California and who now directs the University of Michigan team.
"Andrea is a really good man and he was there in some of the toughest moments of the past three years," Cavic said. "He was there in Munich, right after my operation he visited me. He did everything in his power to help me out when we were working together, but the truth is our relationship was like a really, really bad marriage.
"We just didn't see eye to eye on a lot of things. I didn't like the way he was coaching. He didn't like the way I was swimming. I hated coming to workout and I hated working for him," Cavic added. "It just came to a point where I didn't want to take it anymore. I decided what was best for me at this point was to make a move, because I didn't believe I could be successful with him in the final stage of the Olympics."
Cavic called Bottom "an amazing master of technique."
"Waking up in the morning was never really an issue since I moved over to Mike and I really feel like I was reborn since returned to him," Cavic said. "I feel if I got a chance to do something at the Olympics, Mike will be that man to help me achieve my goals."
Still, Phelps might be beyond reach.
At the U.S. trials earlier this month, Phelps won the 100 fly in 51.14 seconds. Cavic claimed his European title in 51.45.
Tyler McGill, the second-place finisher at the U.S. trials, also had a quicker time than Cavic, touching in 51.32.
"I hope I can get under that 51 mark, because I'm going to have to," Cavic said. "I don't know how, I don't know what I'm going to fix, but I have to. I've got to figure it out. ... I wouldn't be here today if I didn't think I could win a medal at the Olympics. What colour that might be I don't know."
By the time the 100 fly final rolls around on Aug. 3, Phelps will already have swam several events, while it's Cavic's only individual event.
Cavic might take part in the 4x100 freestyle relay for Serbia on the second day of the pool competition, "just to get a feel for the pool and racing."
As for tactics, neither Phelps nor Cavic have changed much.
Phelps likes to pace himself in the first lap then make a mad splash for the wall in the second 50, while Cavic usually takes a large lead at the turn and suffers at the finish.
But Cavic is hoping that his improved training following surgery makes a difference.
"I definitely lost a lot of speed but my aerobic condition has definitely improved," he said. "I expect to be a whole lot stronger."
In Beijing, Phelps' victory depended on a last little stroke and a harder slap on the electronic touch pad, while Cavic hit the wall with just his fingertips.
He'll never make that mistake again.
"You just attack it," Cavic said. "You do not make love to the wall, you attack it."
Cavic isn't interested in revisiting the 2008 race, the results of which produced a protest from Serbia.
"We're going to let that one lie in the past," he said. "I'm pretty comfortable with my past and there (are) no negative feelings toward Michael and there never was."
Like Phelps, Cavic is planning to retire after the London Games
"At this point, nothing else motivates me. It's just all about the Olympics, and if I could win an Olympic medal, that would be the perfect ending to my career," he said.
"If I don't win a medal, I just hope that when I touch the wall I'm going to feel that inner peace, knowing that I gave everything that I could," added Cavic, who is 28. "I'm no longer a kid. I'm ready to walk away as soon as this Olympics is over."
Cavic already has plans for his post-swimming career.
"I'm a candidate for the athlete commission of the IOC," he said. "I hope I get elected to that, and that would be one step toward what I hope to get into someday — sports politics."