Battered from hours of exhausting play during the last few days of the Australian Open, the world No. 1 could have surrendered to Federer during the final. But weariness would be too feeble an excuse for someone too stubborn to be submissive.
Instead, the increasingly mighty Nadal won his second straight five-set match -- his semifinal win over Fernando Verdasco set an Australian Open record when it went five hours, 14 minutes -- beating Federer in a dramatic 7-5, 3-6, 7-6 (3), 3-6, 6-2 final.
"I would never, ever, ever put one dime on him to win this match in five sets, and in fact, it was Roger that got tired," multiple Grand Slam champion Martina Navratilova said. "For Rafa to be able to keep that up is just the most amazing physical display I've ever seen. That he could do it after that match two days ago is astonishing."
The outcome of the Australian Open presents a serious problem for Federer, often anointed the best to ever play the game. He's a guy accurately described as an Einstein with a tennis racket, a genius with breaking records on his mind. Alas, in his way is a larger-than-life Nadal who keeps getting better.
Could the 27-year-old Federer break Pete Sampras' record of 14 Grand Slam titles? Absolutely. He was playing to tie Sampras in this final.
But the truth is the tennis world is starting to say Nadal's name when it talks of who will win the most Grand Slam titles in history. Although Nadal plays a physical brand of tennis and his knees already pain him, he's young and owns a half dozen Grand Slam titles.
"I've said from the beginning, I think that Nadal wins more majors than Roger," seven-time Grand Slam champion Mats Wilander said. "If he physically keeps up, I think he wins more than anybody. Now he's proven he can play on hard courts. He can be the boss everywhere."
Former player-turned-TV-analyst Justin Gimelstob, who couldn't find enough superlatives to describe Nadal's winning performance, agrees with Wilander.
"If he stays healthy, he has the ability to ratchet up Grand Slams beyond the ability Roger and Sampras had," Gimelstob said. "He's 22, and he has six Slams. Do the math. He's a huge threat. The record goes through him. Whatever Federer ends up, Nadal is always a threat to surpass it because there's nothing he can't win. And he's a freak, physically, and I mean that in a positive way."
The confidence Federer once exhibited that he will break Sampras' record definitely received another blow in Australia, as Nadal showed he can beat him at a Grand Slam level on clay, grass and hard courts. Federer was so disconsolate on court after the match, he dissolved into tears and could not speak.
That's because with every match they play, Nadal shows himself to be the more impressive talent.
When Federer isn't facing Nadal, it's a safe bet the Swiss thinks he's the better player. But when he looks across the net to see the muscular Spaniard with the deceitful southpaw style, Federer becomes a fragile talent. Proof of that is a look at their career records against each other: Nadal now holds a 13-6 record, has won their past five matches and owns a 6-2 edge in Grand Slam meetings.
The clear-cut Nadal advantage brings to question how to judge their rivalry: Is it one of the greatest, or not so great?
"It's the greatest tennis ever played," Gimelstob said. "They still have a lot more chapters to write, but to have two of the last three Grand Slam finals be this epic, it's unfathomable what's possible. I think in terms of what they do to each other, this is the best tennis ever played. What they're challenging each other to do on every point is insane."
The other side takes note that Nadal is separating himself from Federer by a very wide margin.
"I think it was potentially one of the greatest rivalries in the history of the game, but it's turning out not to be," Wilander said. "It's an unbelievable match, it's very attractive to watch it.
"It's not Borg-McEnroe where they're both winning until Borg quit. It's not quite Sampras-Agassi. It's a little bit like that because Sampras had Agassi's number, but Agassi won enough and Agassi played longer than Pete. It's just not the same. This is a serious rivalry that's become one-sided, literally."
And what does Nadal have to say about it all? He left happy he has six Grand Slam titles and vowed to continue to work hard to win other titles. And, as always, he paid homage to Federer.
"Today was a lot of emotions on court," the humble Nadal said. "I was there with the best player I ever saw."
Sandra Harwitt is a freelance tennis writer for ESPN.com.