Juan Martin del Potro served notice on Saturday that he's a force again in men's tennis by upsetting No. 1-ranked Rafael Nadal, 6-2, 6-4, in the semifinals of the Shanghai Masters.
Del Potro, who has climbed back to No. 5 in the world after a debilitating wrist injury cost him most of 2010 on the tour, will play second-ranked Novak Djokovic in the finals. Djokovic beat Jo-Wilfried Tsonga, 6-2, 7-5, in the other semifinal.
The last time Del Potro defeated Nadal was in the semifinals of the 2009 U.S. Open, which happens to be the only Grand Slam singles title of the Argentine's career.
The top-ranked Spaniard was impressed by the play of Del Potro, who had been a regular member of the top 10 when healthy since his breakthrough year.
"Very few times I played against a player with a level like today I played against," Nadal said. "At the end, I played against a player who served 80% of first serves, who hit every ball as hard as he can, I think, and with no mistakes."
Del Potro, who won last week at the Japan Open, qualified for the ATP Finals in London, where he'll get to battle Nadal, Djokovic and third-ranked Andy Murray for season-ending supremacy.
The Argentine knew he had a winning combination Saturday.
"I played so solid all the time, hitting so hard the ball," Del Potro said. "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."
Wire service and Internet reports contributed to this story.