You can have the Super Bowl. The Australian Open final between Federer and Nadal reminded me of what I’d thought after last year’s Wimbledon: this wasn’t simply tennis at its highest level but sport itself at its ultimate: two athletes in direct opposition and tested to the last measure of mind, body, temperament, and character. And of these, character ultimately seemed to matter most, for the tennis the two of them play against each other is brutal – rally after rally lasting a dozen or more strokes and eventually resolved by a brilliant stroke, or dumbfounding error, that visibly exhilarates one and batters the other. Yet what do they do? They study their rackets for an instant and play another point.

It’s as personal a confrontation as a prize fight. But boxers may settle matters in minutes; the trial tennis puts these players through lasts three, or four, or five hours. The tennis we saw in the first set of one of these matches seems separated by an eternity from the tennis we’re watching in the fifth.

After the Australian final was over I contacted the best tennis player I know — Del Campbell, a retired army colonel who’s played all his life and early last year, before knee surgery knocked him out of competition, was ranked first nationally among players 65 and older. Del thinks Nadal and Federer are the two best tennis players who ever lived, and his belief is that after the first game of the fifth set, “Nadal knew he had him.”

I went back and watched that game again. Nadal had struggled to hold serve all match long and been broken several times. But he won this game easily, as Federer mishit two returns. The mystery was Federer’s sudden loss of form. Nadal had gone into the match having barely survived a five-set, five-hour semifinal played a day later than Federer’s semi, which Federer swept. Nadal had started to show fatigue in his third set against Federer, though he won it in a tie-breaker, and in the fourth set he couldn’t break Federer when the opportunity came and then Federer had taken over the set and won it easily, 6-3.

Federer entered the fifth set the fresher of the two, the more experienced of the two in playing for major championships, and the one playing the better tennis. Yet he fell apart. Nadal, who so far as I could see hadn’t lifted his own game an inch, won the last set 6-2 and accepted the trophy as Federer wept.

So what happened? “I think Federer himself doesn’t know,” Del said in our exchange of emails. “You can bet Roger and his girlfriend, herself a tournament player, pondered that all day. Was Federer nervous? With all his experience in big matches, one wouldn’t think so. He didn’t look nervous, but then he never does. Maybe he was slightly tired and just didn’t show it. If his reflexes were 1-2% slower this would be enough to cost him a match at the level of tennis he and Nadal were playing.”

Del said the “tactical reason” Federer lost was his serve, which he couldn’t trust at any time in the match. Was his serve a clue that Federer never felt in control of his game, no matter how strong it looked to someone like me, and simply lost it altogether in the fifth set? Did he look across the net at Nadal thinking that the fourth set should have cracked Nadal wide open, and then remembered that Nadal doesn’t crack and realized that whatever he’d done to Nadal in the last set he’d be starting from scratch in the fifth? Maybe. “I think after two weeks of pounding on the concrete courts at the Aussie Open, and concentrating for five hours of superlative tennis in this final match, I think Roger was mentally tired,” Del wrote. And at that moment, was Federer’s history of winning championships like this one not an advantage but a burden? Del thought it might be.

“Maybe he is stubborn and won’t adapt because he’s never had to. Maybe, despite his huge successes, he needs a coach (as Patrick McEnroe suggested). Maybe he looked across the net and realized that he couldn’t beat Nadal. Roger has played and won for 16-18 years—perhaps it’s burnout.”

What had fascinated me about Federer’s collapse when it happened was the way it violated all rhyme and reason, and I was grateful to Del Campbell for not trying to explain it away. I like to believe that some things happen for reasons that are simply unknowable, and Del didn’t pretend that to the expert eye they don’t.

“I’ve played two five-set matches in my life,” he wrote. “Won a singles match in 3 sets once, and won an unbelievable doubles match in Europe when I was about 25. My partner was a Bolivian Davis Cup player. We were playing two guys from France — won the first two sets 7-5, 7-5. Their coach came out and talked to them — they won the next two 6-0, 6-0 !! (what in the world did he tell them?????) They went up 2-0 in the 5th set — and we ‘raised our level’ ( i guess) and won 6 straight games. Four-hour match on clay.”

The ebb and flow of that match makes no sense at all. (What did he tell them, and did whatever he told them have anything to do with what happened?) It’s just the way it was.