Juan Martin del Potro has taken down the world’s No. 1 player in China…

The 25-year-old Argentine tennis player defeated Rafael Nadal, who just returned to the top of the world rankings after an impressive run this year, 6-2, 6-4 in the Shanghai Masters semifinals on Saturday.

The fifth-ranked del Potro will now attempt to win his first Masters title on Sunday against top-seeded Novak Djokovic, who defeated Jo-Wilfried Tsonga in the other semifinal 6-2, 7-5.

del Potro hadn’t beaten Nadal since the semifinals of the 2009 U.S. Open where he went on to win his only Grand Slam title.

But del Potro is playing fully fit and confident — he’s coming off a win last week at the Japan Open that returned him to the top five in the rankings for the first time in three years.

He completely overpowered Nadal with his deep, punishing groundstrokes and fended off all six break points he faced.

Nadal’s serve, on the other hand, was under threat during the entire match. After not dropping serve in 28 games this week, the Spaniard was broken twice to start the match as del Potro raced out to 4-0.

Del Potro started to make a few mistakes in the second set, giving Nadal two chances to break in the second game. But the Argentine saved both with huge serves and put the pressure right back on Nadal, breaking him for a third time in the following game.

“I played so solid all the time, hitting so hard the ball. I saw Rafa playing very far off the baseline, which is good for my game, for my serve and confidence. That’s the way to beat this guy,” del Potro said.

Nadal said he hadn’t seen del Potro play this well in years. Or anyone, for that matter.

“Very few times I played against a player with a level like today I played against,” the Spaniard said. “At the end, I played against a player who served 80 percent of first serves, who hit every ball as hard as he can, I think, and with no mistakes.”

del Potro wrapped up a spot in the ATP Finals in London with the win. He’s been working his way back into top form since a wrist injury knocked him off the tour for most of 2010 — just after he got his breakthrough win as a 20-year-old at the U.S. Open.