Eighth seed Gael Monfils upset number two Fernando Gonzalez of Chile 6-3, 7-6 on Friday to advance to the semi-finals of the Vienna Open.
The 22-year-old Frenchman put in a gutsy performance, saving seven out of eight break points before dominating the tiebreak 7-2.
Monfils, a former junior world number one, is through to his fourth semi-final of the year but is yet to reach a final in 2008.
Standing in his way on Saturday will be German world number 32 Philipp Kohlschreiber who cruised past fifth seed Fernando Verdasco of Spain 6-2, 6-3.
The unseeded Kohlschreiber broke twice in each set without being taken to a single break point on his own serve.
The 24-year-old is chasing the third ATP title of his career, having won his second in Auckland at the start of this year.
German qualifier Philipp Petzschner and unseeded Spaniard Feliciano Lopez will meet in Saturday's other match.
Petzschner, the world number 125 who stunned top seed and world number 10 Stanislas Wawrinka in the first round, booked his first appearance in an ATP semi-final with a 6-4, 6-2 win over former world number one Carlos Moya.
Lopez, who won his only previous ATP singles title at the Vienna Open four years ago, fought back from a set down to see off Austrian Juergen Melzer 4-6, 6-3, 6-4.