Newly-crowned French Open champion Rafael Nadal lost in the first round of the Halle Open in his first competitive match on grass this season. Germany's Alexander Waske beat the Spanish teenager, who had only one day to prepare for the match, 4-6 7-5 6-3.
Nadal, who beat Mariano Puerta for his first Grand Slam title at Roland Garros on Sunday, had not lost in 26 matches.
Meanwhile Marat Safin went through to the quarter-finals when Fabrice Santoro was forced to retire in the third set.
Comparing the defeat to his victory at Roland Garros, Nadal said: "Today was totally different. He served well and I could not play my best tennis on grass within these couple of days."
Waske, who had lost both his previous two ATP matches this year, was humble in victory, saying: "Nadal has just turned 19 and I think he has a great
future ahead of him.
"He will definitely be giving spectators a lot of pleasure in the years to come."
Australian Open champion Safin was handed his 3-6 7-6 3-2 victory when Santoro quit with a heavily-taped left thigh.
Safin, who had a knee injury of his own, said: "It's very painful. On some serves I can't jump.
"But I will play Wimbledon and then take a month off."
Safin had lost to the Frenchman in seven of their previous eight matches.
He looked set for an eighth defeat when trailing 6-5 in the tie break before forcing the match into a third set.
Santoro then picked up his injury in the second game of the final set which eventually forced him to bow out.
"He didn't move very well - I was just waiting to break his serve, then I knew he would quit," said Safin. "I think I played very well today."