IF YOU saw Rafael Nadal on Saturday night (when he slaughtered Tommy Haas) and you saw Roger Federer today, you might think, no way is the Swiss going to win this Open. Nadal was scary, there is no other word. Federer, who struggled and then toughed out a win against Tomas Berdych 4-6, 6-7, 6-4, 6-4, 6-2, was average for two sets.

Then again, one day is insufficient proof of anything. Even for the great players, tennis is a day to day business. Against Marat Safin, the Fed had a good day. Today was a bad one. Difference is he knows how to win even on his off days.

This was the first of many sporting truths reinforced on a riveting day. Second was that for all the talk of Andy Murray's muscles and Nadal's speed, this old 27-year-old Swiss bloke (the Spaniard is five years younger, the Scot is six years younger) is not too bad in the fitness department.

Thirdly, while fitness matters, it's anyway about more than just the body. Baseball player turned maths genius Yogi Berra once said: "Baseball is 90 per cent mental. The other half is physical." Tennis is no different. Which is why Federer said: "I don't know how fit Murray is. I'll take him on any day in a five-setter. He's younger, so he's probably not so experienced. In the end it becomes very mental and I know that is where my biggest strengths come into play. That's why I'm always going to favour myself in a fifth set." .

Fourth, Federer looks a well-dressed, designer hair-cut, RF-logo wearing dude, with a game so beautiful (at its best) it looks made by Prada. But you don't win 13 grand slam titles unless you're a scrapper. There's no pretty boy inside him, there's a streetfighter. Asked what he was thinking when he was two sets down, he said: "I wasn't thinking of losing. The finish line was still very far for Tomas. I knew that. You can still concentrate on playing just the points instead of thinking, 'Oh my God, what's going to happen'."

Fifth, good players can play great tennis but usually not for long enough. Tomas Berdych, who beat the Swiss the first time they met in 2004, couldn't miss a ball for two sets even if he had closed his eyes. There wasn't a line he didn't hit, a winner he didn't construct. But Federer didn't panic because he knew that the standard had to dip, even a little. It did.

Sixth, champions are different beasts when it comes to major tournaments, and Berdych recognised this. As he said: "The best way to beat him (Federer), especially in a grand slam, is in three sets. If you leave him to win one, two sets then he's going to be stronger and stronger. That's just happened today".

One final thought. If fans of Murray, Djokovic and Nadal are grinning and thinking, no way is this model of Federer going to win the Open, here's an omen to make the Fed fans feel better. At the last grand slam event, the 2008 US Open, Federer also played a five-setter, also in the fourth round, and also won it (against Igor Andreev). He then went on to win the tournament.