German qualifier Bjorn Phau upset second-seeded Mikhail Youzhny to reach the quarterfinals of the Zagreb Indoors on Thursday.

Phau beat the Russian 4-6, 7-5, 6-1 and will compete in his first quarter-final since Stuttgart in 2012.

Youzhny, the 2012 Zagreb Indoors champion, was playing well until he lost his serve in the second set when he foot-faulted. Phau used the opportunity, won four games in a row and turned the match around.

"It was not the foot fault that caused me to lose the match," Youzhny said, adding he felt sick during the play.

Daniel Evans of Britain also reached the quarter-finals, beating Michael Berrer of Germany 1-6, 6-1, 7-6 (4). Dudi Sela of Israel also advanced, defeating Lukas Lacko of Slovakia 6-3, 6-2.