This week, whenever I’ve heard Michael Phelps being interviewed after his races, I’ve been reminded of Roger Federer. This isn’t because the two men sound all that much alike. Phelps appears to get tongue-tied when asked to describe what he does in the pool, or how he feels once a race is over. These were the words he used to sum up his emotions after he won his record eighth gold medal in Beijing in 2008: “It’s something I’ll never forget.” (Really, are you sure you want to go that far out on a limb?) Federer, on the other hand, tends to ramble, and has been known to end up with his foot in his mouth. What unites them in my mind is that these two athletes, who may be the best their sports have ever seen—Olympian is the only word for both of them—are doers, not speech-makers or analysts. They express themselves so thoroughly when they play and swim that there’s nothing else that needs to be said, or can be said.

Federer and Phelps, each of whom has had a starring role in London this week, have more in common than just excellence. Personality-wise, they’re both a mix of the supremely confident and the slightly awkward—aside from a bonghit or two (or more) by Phelps, no scandal has been attached to their names. In terms of their careers, each can fairly be called aging: Phelps is 27, Federer is nearly 31. Each made his first Olympic splash, and fell in love with the Games, back in Sydney in 2000. This year each of them has noted, wistfully, that he’d love to be able to recapture the feeling he had then, but that things change. Federer has hinted that the Olympic spirit may be enough to keep him in the sport until Rio in 2016. Phelps claims that this is his final Games, though last night, while he was trying—again without much success—to describe how he felt about swimming the last Olympic semifinal heat of his career, he seemed to waver on that vow just a little bit. NBC commentator Rowdy Gaines says he thinks that Phelps will get bored sometime in the next few years and change his mind. With four Grand Slams to play for each season, it will certainly be easier for Federer to keep his head, if not his body, in the game until 2016.

Federer and Phelps both came to London with younger rivals at their heels, rivals who, at various times, have appeared destined to pass them for good. As recently as two months ago, Federer was ranked No. 3 in the world, hadn’t won a Grand Slam since 2010, and had watched the two best players from the next generation, Rafael Nadal and Novak Djokovic, contest the last four major finals. As for Phelps, after a few years of indifferent training, he had ceded the spotlight to his fellow American, and omnipresent cover boy, Ryan Lochte. When Lochte won gold in their first showdown and Phelps finished fourth, Federer may have felt a sense of deja vu about the general reaction. Suddenly, Lochte was the new great U.S. swimmer, the future of the sport, the man who showed that Phelps was mortal after all. A couple of days later, Chad Le Clos, a younger swimmer from South Africa who Phelps has, in the words of the New York Times, “seemingly tapped as his successor,” did what the American had done to so many others, tracking him down and out-touching him for gold in the 200-meter butterfly. It seemed that even Phelps’s formerly airtight legacy could be in danger of being damaged by his London Games' performance.

Federer’s version of Lochte and Le Clos are Nadal, Djokovic, Andy Murray, and, today, Juan Martin del Potro. All four are younger, and all use solid baseline games with two-handed backhands, a style that has long been predicted to be the future of the sport. Each time one of these players has beaten Federer, there’s been talk of his decline, and how his one-handed game is outdated.

While Del Potro overpowered Federer in the 2009 U.S. Open final, this year Federer, as he said yesterday, has “had his number,” beating him all five times they’d played. But from the first points of their semifinal on Friday, it was clear that this was a different del Potro. His shots sounded heavier; it looked like he would power his way into the gold-medal match. While he didn’t do that in the end, del Potro may have done something greater by showing the world how much heart he could muster while playing for his country, and how much the Olympic Games have inspired the tennis players of this era. In what would turn out to be an epic 19-17 third set, and perhaps the best match of 2012 so far, del Potro never gave in mentally. He came up with shots and gets and diving volleys that I had never seen from him before. He was also the picture of tennis intensity throughout. The emotional Argentine was working so hard through the third set that it looked as if he were on the verge of tears. It was, in truth, a pained grimace of concentration and will.

As happy as I would have been to see del Potro go for gold—it would have capped his agonizingly long comeback from wrist surgery—I had trouble imagining Federer receiving, or accepting, a bronze. It would have been as strange as the sight of Phelps standing below Lochte on a medal stand. Federer had the crowd behind him on Centre Court today, as he almost always does, and I think part of that is a desire among sports fans to see a legendary athlete’s story end the way we think it should end. I feel the same way about Phelps. I’m sure there are plenty of swimming aficionados who are tired of his dominance and want to see him brought down a notch, just as there are those in the tennis world who have grown weary of Federer’s lionization. But as an outsider to swimming, I want to see the king of the pool remain on his throne. I want to see him crush all of the young punks and challengers, because...because why, exactly?

I think it’s because I want to believe in mythic figures, people who are beyond the flaws that make the rest of us human. I want to shake my head and say, “Wow, Michael Phelps is incredible,” rather than saying, “Well, everyone gets older and you can’t win them all.” I don’t want the myth to be punctured. I think this is the way a lot of people also feel about Federer. Fans want him to show that he can vanquish the younger generation, take back No. 1, win more majors, and finally earn gold.

The Olympics in general highlights the absurdity of competition; it can blur the line between skill and luck beyond all recognition. A runner may train every day for four years, beat everyone in the world during that time, and with one trip on a hurdle end up with nothing. This week we’ve seen gymnast Jordyn Weiber, the best in the U.S. heading into the Games and the current world champion, make a few mistakes at the wrong time and end up not even being able to compete for the gold. This takes nothing away from the winner, Gabby Douglas, who was nothing if not clutch. It’s just tough to see a one-day performance have such permanent consequences. It would be one thing if Weiber could come back and try against next year, the way most athletes can, but chances are this will be her last Olympics.

It would have been equally tough for Federer to know that, despite his dominance virtually everywhere else, all of his efforts at singles gold over the years would have been stymied. Just as bad, a player he had beaten five times in one season would have turned the tables on him at the most inopportune moment. If, serving at 11-12 in the third set, down 0-30, Federer hadn’t come up with four unreturnable serves, that’s what would have happened. But Federer did come up with those serves. On a day when he walked out with his B game, he simply refused to let himself lose. You could feel, in both men's performances today, the weight of the four-year gap between Games.

And that's also a big part of Federer’s and Phelps’s appeal: They make sports seem less random, less about the blind luck of the day. Federer didn’t give in to what appeared to be his fate. He won with his serve, with his speed, with his fitness; none of these things appear to have been diminished over time, the way they are for the rest of us. The same went for Phelps over the last two days. First he got revenge on Lochte in their second duel, in the 200 IM. This afternoon, he turned back the clock one more time and tracked down Le Clos for one last gold in the 100 meter butterfly.

In between those two races, Phelps did something he had never done before: He won a third Olympic gold in one race. I was amazed to see how much it meant to him. He has won more medals than anyone and more golds than God, but after he won this one, he found the camera and stuck three fingers out, to indicate his three-peat. He looked like the 15-year-old version of himself in Sydney who had just won his first race. That’s one more thing Phelps has in common with Federer: A desire, even after they’ve proved all they can prove, to do more. Two days later, Federer did something he had never done before; he reached his first gold-medal match.

We’ve watched one king vanquish his young challengers and make his Olympic story end in triumph. On Sunday another will try to do the same. This time Federer will have to recover from a grueling match, in front of British fans who will likely want to see him deposed by their own man, Andy Murray (though Federer will have his supporters). We’ll see if can make his myth grow a little more by overcoming all of that. It would, despite how good Murray obviously is, be strange to see him standing above Federer on the podium afterward. Federer himself knows how much it means. Today, with his emotions swirling after his win over del Potro, he found the right words to describe how he felt living up to his countryman’s expectations and becoming Switzerland’s first medalist of these Games. “It’s big, it’s big,” Federer said in a near whisper as he walked away. The biggest, the last chapter of this London story, is yet to come. Which song will be the right one to sing when it's all over: "God Save the Queen," or "God Save the King"?