Andre Agassi's French Open preparations suffered a major setback when he crashed out in the first round of the Raiffeisen Grand Prix in Austria.
Agassi was making his debut on European clay this year after electing to miss the recent Masters Series tournaments on the surface.
But the top seed lost 6-2 7-6 (8/6) to doubles specialist Nenad Zimonjic.
Agassi has seven days to rediscover his form ahead of the French Open, which begins on 24 May.
The American had not played since March 30 when he lost in the fourth round in the Nasdaq-100 in Miami.
"Zimonjic played great tennis. It was very hard for me to
guess what he was going to do next," he admitted.
"It is an unbelievable feeling and a great honour to have
defeated Andre Agassi," Zimonjic said.
"I was really lucky, because he lacked match practice and thus could only show his great skill occasionally."
In other matches, Croatian seventh seed Ivo Karlovic beat Andrea Stoppini of Italy 6-7 6-4 6-3, and Belgian Olivier Rochus thrashed Israel's Harel Levy 6-1 6-1.
Home favourite Stefan Koubek saw of Sweden's Robin Soderling 7-5 7-6 (7/3).