Gael Monfils failed to clear the first hurdle at the ATP Erste Bank Open, losing 7-6 (7/0) 7-5 to Jaroslav Pospisil in Vienna.
The sixth seed from France failed to find the same form he had shown in defeating Roger Federer in Shanghai the previous week, losing a first-set tie-breaker to love.
He battled back from a break down in the second to make it 4-4, only to then crucially lose his serve again to his Czech opponent in the 11th game.
"Credit to him, he played well, but it was more about my body and my lack of game," said Monfils afterwards. "He was playing tough but I was just not ready. I'm not happy with tonight.
"I tried hard, I did the best I could, but it's not easy to come from outdoors (Shanghai) and adjust to an indoor court in only a few days. This is tough to take."
Pospisil's success was even more impressive considering he wasn't initially in the main draw, only getting a place hours before he appeared on court due to Australian Marinko Matosevic pulling out with a shoulder injury.
There was also good news for his compatriots Radek Stepanek and Lukas Rosol, the seeded duo both reaching the quarter-finals with straight sets wins.
The fifth-ranked Stepanek needed nearly two and three-quarter hours to defeat Lukas Lacko 7-6 (7/4) 5-7 7-6 (7/5), while Rosol - the eighth seed - saw off Mirza Basic of Bosnia-Herzegovina 6-3 7-5.
Top seed Jo-Wilfried Tsonga begins his campaign with a second round clash against German Daniel Brands.
Frenchman Tsonga, who says he is nearing an appointment of a new coach, lost to eventual champion Novak Djokovic in the semi-finals in China last week.
He needs to keep earning ranking points if he is to be assured of qualifying for the season-ending ATP Tour Finals in London. He does, though, have good memories of the Austrian event, having lifted the trophy in 2011.