Second seed Roger Federer was dumped out of the Swiss Indoors by a 7-6, 6-7, 6-4 second-round defeat at the hands of Croatian Ivan Ljubicic.
The Wimbledon champion failed to secure the victory his home crowd at Basel's St Jakobshalle wanted as world number 47 Ljubicic took a surprise, but deserved, win to reach the quarter-finals.
Swiss Federer, who had won his last two matches against Ljubicic in Dubai and Marseille earlier this year, was made to pay for a below-par first serve and a number of unforced errors.
Ljubicic, 24, broke at the start of the third set and, despite being troubled by cramp, he served out to win a contest that lasted two hours 23 minutes.
"It was probably one of the best games I've played this season," the big-serving Croat told reporters. He will now face Ecuador's Nicolas Lapentti, who beat German Tomas Behrend 7-6, 6-1.
"I played the important points well and my serve was very good. It was a huge advantage to get the first set on the tie-break and I had match point in the second set," said Ljubicic.
Federer's hopes of ending the year as number one in the world suffered a blow but the six-times title winner this season admitted suffering fatigue following a heavy schedule in 2003.
"Not very good," was the twice Basel runner-up's assessment of his performance. "I didn't play my best tennis and he played well. That was it."
Earlier, top seed Andy Roddick came back the stronger from two 20-minute interruptions, one in each set, because of light failures to beat qualifier Gilles Elseneer 6-3, 7-6.
FLASH LIGHTING
Roddick broke the Belgian each time the match restarted before producing the goods in a second set tie-break, including a blistering ace at 5-5.
"I'll pack my own flash lights tomorrow," joked the American, who will play another Belgian, Olivier Rochus, in the quarter-finals.
"It's just annoying because you are mentally into the game and you don't know when it will come back on, or if it will come back on. It's frustrating."
Organisers said the problems came as a result of a power failure in another area of the town.
Defending champion David Nalbandian, the fourth seed, also went through after Frenchman Arnaud Clement was forced to retire with a thigh injury.
Nalbandian, who defeated Chile's Fernando Gonzalez in last year's final, won the opening four games and Clement retired after making it 4-1.
The Argentine now plays Tim Henman after the Briton disposed of Czech "lucky loser" Tomas Zib 6-3, 6-4 in the final match of the day, which was also interrupted by lighting problems.
Third seed Guillermo Coria, returning from injury, joined fellow Argentine Nalbandian in the last eight with a 6-2, 6-7, 7-6 victory over French qualifier Michael Llodra.
But fifth seed Jiri Novak of the Czech Republic was knocked out 3-6, 7-5, 6-4 by Feliciano Lopez of Spain, who will now take on Coria.
Tommy Robredo, seeded eight, slumped to a 7-5, 6-1 defeat by Rochus, who had lost his previous two encounters with the Spaniard.
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