Thomas Muster of Austria rallied from a 4-1 deficit in the opening set and shocked Pete Sampras 7-6 (8-6), 6-2 in the semifinals of the Eurocard Open.
Unseeded MaliVai Washington won the other semi, beating Arnaud Boetsch of France 7-5, 6-2.
The title match in the $2.1 million event will be played today.
Sampras, seeded second and ranked No. 2 in the world, dominated in the early phase of the match against Muster.
But the Austrian tamed the American’s serve, broke back and turned the match around.
The defeat delayed Sampras’ move to the world No. 1 ranking.
Sampras lost the No. 1 spot to Andre Agassi on April 10, and will now have to wait at least until next week’s Paris Open to climb back atop the rankings.
Agassi is out of action for about a month with a strained chest muscle.