Rafael Nadal may be the world’s second-ranked player, but he was the second best player on the court yesterday against Mikhail Youzhny.

The unseeded Russian exposed Nadal’s weaknesses and pulled off by far the biggest upset of this U.S. Open, a 6-3, 5-7, 7-6 (5), 6-1 quarterfinal stunner.

The tennis world may have been salivating over a Nadal-Roger Federer rematch, which would’ve made them the first in history to meet in three Grand Slam finals in one year. But a funny thing happened on the way to that dream final – a 24-year-old Russian playing the best tennis of his life, with nothing to lose.

“I want to thank [the crowd]. You came for Rafa, but during the match you changed your opinion,” said Youzhny, who clinched it the way he’d earned it – attacking Nadal’s forehand. Then he saluted the Arthur Ashe crowd he’d won over with his daring style, turning Rafa! Rafa! to Misha! Misha!

“It was my best match. I have only one chance to beat Nadal. If I play like I did [yesterday], with my head,” said Youzhny, who did his best work with the chips down. Nadal led 5-4 in the third with triple set-point. That’s when an unfazed Youzhny turned the tide.

“I didn’t have time to think about it. If I [did], I’d lose. For me to play Rafa was easy, because I lose nothing. He’s the favorite, one of the best in the world. Love-40, I just play.”

That he did. After Nadal missed his serve at love-40 to open the door, Youzhny crashed through, winning five straight points and then the tiebreaker.

Leading the tiebreaker 5-4, Nadal hit a forehand that hit the net and actually sailed long. The Spaniard could only smile wanly at his misfortune, but it was about to get worse. Youzhny followed with an ace to go up 6-5, and took the tiebreaker when Nadal couldn’t return his forehand. In the fourth set, Youzhny took control. Nadal’s usual energy got sapped from him, and he hung his head.

“I am trying to fight, but I wasn’t . . . I was not at my best in the fourth,” said Nadal, who refused to use last match’s ankle injury as an alibi. “If I lose, I lose. No ankle, no pain, nothing.”