A fatigued Rafael Nadal could not prevent the brilliant Jo-Wilfried Tsonga prevailing 6-7 6-4 6-1 in their quarter-final match at Queen's.
The two players went toe-to-toe in the first set, with the world number one winning a close tie-break.
Tsonga then broke in the first and ninth games of the second set to level.
Nadal surrendered in the third set, a combination of the Spaniard's sloppiness and Tsonga acrobatics securing victory for the Frenchman.
The Frenchman was clearly delighted and, with a beaming smile, told BBC Sport: "The victory means a lot, of course, because he's the best player in the world and I'm just happy.
"The first time I entered the top 100 it was here and to win against the world number one...
"To beat Rafa I had to play my best and I just played great. It was just amazing, the atmosphere, and I feel good here so I just hope I play well in the next round. I just tried to stay focused in the match and I did it."
Tsonga will play Britain's James Ward for a place in the final against the victor of the semi-final clash between Andy Murray and Andy Roddick, who earlier beat seventh seed Fernando Verdasco 6-2 6-2.
After a day interrupted by rain delays, Nadal admitted that his focus had wavered, but reflected that defeat may actually improve his preparation for Wimbledon.
"Probably after losing the second set mentally I lost my concentration," said the 25-year-old.
"The negative thing is I lost. The positive thing is I have few days off and can stop a little bit mentally. I can be a little bit more relaxed, because every day I play with pressure."
After the match, the world number one said he planned to head home to relax before returning to Britain for Wimbledon with "high motivation".
"Probably after losing the second set mentally I lost my concentration," he added.
"The negative thing is I lost; the positive thing is I have few days off and can stop a little bit mentally. I can be a little bit more relaxed, because every day I play with pressure.
"That's what happened for me the last four months every day."
World number 19 Tsonga was in inspired form on Centre Court, with the match eventually getting into full swing after the weather had forced the players off court with just the first two points played.
Nadal looked well below his best, with the exertions of winning a record sixth French Open clearly affecting his performance.
But Tsonga impressed in every aspect of the game, serving 25 aces and delighting the crowd with acrobatic play near the net.
Tsonga had his chances to win the first set, but the French Open champion recovered from break-point down in the sixth game and went on to win the last five points of the tie-breaker.
Nadal was making uncharacteristic errors from the baseline and when Tsonga broke twice early in the third set, the Spaniard's body language suggested the match was all-but over.
Tsonga dominated the remainder of the match, sealing victory with a brutal forehand winner down the line.