Fabio Fognini shocked top seed Tommy Haas to reach the semi-finals of the Mercedes Cup in Stuttgart for a second time.
The Italian prevailed 6-4 6-2 on Friday to set up a last four clash with Roberto Bautista Agut, who advanced when German opponent Michael Berrer retired with a left elbow injury with the Spaniard leading 6-2 0-1.
Haas saved four match points but hit a backhand wide to send the fifth-seeded Fognini into his third semi-final of the year, with the Italian having lost the previous two in Acapulco and Monte Carlo.
"It's my second semi-final in Stuttgart, maybe I can go all the way," a delighted Fognini said. "I just played my tennis and it worked for me."
Haas admitted he had failed to take his chances.
"I had five break points in the second set and if you don't use them you can't win," the 35-year-old said.
In the other semi-final, second-seed Philipp Kohlschreiber will take on Victor Hanescu, who upset fourth seed Benoit Paire 7-5 6-2.
Kohlschreiber avoided his own upset by seeing-off the challenge of Gael Monfils 6-4 6-4, being two breaks of serve up in each set before closing them out.