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Tsonga, who has competed in just five Grand Slam tournaments, played scintillating tennis from start to finish, smothering Nadal before sealing the match with an ace after one hour and 57 minutes.
The 22-year-old will meet the winner of Friday's other semi-final between Roger Federer and Novak Djokovic, one and three in the world respectively.
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Tsonga looked nervous as he dropped the opening two points but quickly found the rhythm that had already accounted for the seeded Andy Murray, Richard Gasquet and Mikhail Youzhny.
In contrast, Nadal - so often the showman on court - looked subdued and uneasy as he struggled to cope with the blistering groundstrokes and sublime volleys of Tsonga.
The Spaniard failed to recover from dropping his opening service game and Tsonga broke for a second time, with a scorching forehand winner down the line, to seal the first set in just over half an hour.
The opening stages of the second set went with serve, but while Nadal was forced to defend break points as early as the second game, the huge Tsonga serve went largely unharmed.
Although Nadal looked to be imposing himself more as the set went on, Tsonga refused to be intimidated, choosing instead to take the second seed on at the baseline and disrupting his all-important routine.
Just the one break of serve was all Tsonga needed to seal the second set, and it came in the eighth game when he followed a huge forehand with an emphatic smash into the open court. The Frenchman then served out the set to love.
Despite the world number two earning his first set points in the second game of the third set, he was unable to take advantage and promptly surrendered his serve in the very next game, a couple of tame forehand errors gifting Tsonga an easy break.
A visibly deflated Nadal spent the change of ends slumped in his chair shaking his head. He managed to register just one more game while the Frenchman broke again in the seventh game, with another forehand winner down the line, to leave him serving for the match.
Tsonga showed no signs of his inexperience, serving out the match for the loss of just one point to claim a place in Sunday's final.
Tsonga said: "It is just amazing, unbelievable, nothing could stop me today. I tried to hit everything and everything went in, so what can I say? My family said it is like a dream for them, everybody in France is happy for me. I will try to do my best for the final. Rafael plays the same tennis all the time. His level is very high and it's very difficult to play against him. But I was just concentrating on my own game. I was moving on the court like never I move, so everything was perfect."
Nadal said: "We have to accept today he played unbelievable. Playing the ball very hard every time, serving unbelievable. In the backhand he didn't miss not one. Forehand, every time he does the forehand was a winner, so congratulate him. Everything is going good for him. So when you are playing like this, every ball is going to the line. Every ball is going inside. Is not the real level I think. Sure, he can play like this, but not every week. It's impossible."
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