Rafael Nadal is the second-ranked player in the world, but he was the second-best player on the court in yesterday’s U.S. Open quarterfinal against Mikhail Youzhny. The unseeded Russian exposed Nadal’s weaknesses and pulled off by far the biggest upset of the tourney, 6-3, 5-7, 7-6, 6-1.

“I want to thank [the crowd]. You came for Rafa, but during the match you changed a little bit your opinion,” said Youzhny, who clinched it with a point typical of the match, attacking Nadal’s forehand, then saluting the crowd when it was over.

The 24-year-old Youzhny took it to Nadal, hitting a stunning 49 winners while only making 34 unforced errors, fewer than Nadal. The 20-year-old Nadal likes to get his foes off-balance, working them over like a boxer working the body. But with Youzhny’s effortless forehand, he put on a clinic.

Youzhny beat Nadal in their very first meeting, and he did it again yesterday, exposing the Spaniard’s lack of ability at net and his less-than-stellar forehand. And when the lesson was over, Youzhny had killed a potential Nadal-Roger Federer rematch, and reached his first career Grand Slam semi, against either Andy Roddick or Lleyton Hewitt.

After dropping the first set, Nadal took the second and had three set points in the third. But Youzhny won five straight points to make it 5-all, and turned the tide in the third set tiebreak.

Nadal led 5-4, but 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 completely took control. Nadal, used to winning cheap points against foes when they press, had the tactic pulled on him.

The official program handed out to fans yesterday mistakenly had Youzhny already beating the two-time French Open champ; turns out the error was prophetic.

Nadal’s class and ability are unquestioned, but clearly Youzhny has skill, too, as his win over Federer earlier this spring in Dubai showed. Now, after upsetting No. 11 David Ferrer in the third round, drilling No. 6 Tommy Robredo 6-2, 6-0, 6-1 in the Round of 16 – the second easiest of the tourney – and now upended Nadal, he’s beaten three straight ranked Spaniards.