Linz - Former world No 1 Ana Ivanovic was docked a game for taking too long in the toilet but still eased past Barbora Zahlavova Strycova of the Czech Republic 6-3, 6-2 to reach the Generali Ladies quarterfinals on Thursday.
Second-seeded Daniela Hantuchova, who won the event in 2007, also advanced after defeating Carla Suarez Navarro of Spain 6-4, 6-3.
Hantuchova, the highest-ranked player in Linz since Serena Williams pulled out with a foot injury, overcame an early break and cruised to victory afterward.
Ivanovic asked for a toilet break after winning the opening game of the match but the umpire gave her four penalty points - effectively a whole game - upon her return for taking too much time.
The chair umpire explained to the booing audience that she was docked one point for every 20 seconds she went over the time limit.
Ivanovic blamed the incident on "a miscommunication" and said she thought she had been allowed to leave the court.
"I felt a bit sick so I had to go to the toilet," the seventh-ranked Ivanovic told Austrian broadcaster ORF. "I asked the referee and I thought he granted me permission to go so I was really surprised to be punished."
Ivanovic later revealed on her Facebook page she was getting sick after eating yoghurt just before the match.
"I wasn't expecting to go on court so early," she said. "I wasn't aware of the rules and anyway I simply had to go to leave the court because I knew I was going to be sick."
The Serb, who won the event in 2008, said the incident did not put her off.
"It did not disturb my concentration and it didn't really matter because I won the match," she said.
Ivanovic next meets Julia Goerges of Germany, who beat fifth-seeded Petra Kvitova of the Czech Republic 6-2, 6-1 to reach her fifth quarterfinal of the season.
Goerges won her only WTA Tour title in nearby Bad Gastein in July.
Eleni Daniilidou of Greece saved three set points before defeating Austria's Sybille Bammer 6-1, 7-6 (2). Daniilidou next plays sixth-seeded Andrea Petkovic.
Julia Goerges, Germany, def. Petra Kvitova (5), Czech Republic, 6-2, 6-1.
Ana Ivanovic (7), Serbia, def. Barbora Zahlavova Strycova, Czech Republic, 6-3, 6-2.
Eleni Daniilidou, Greece, def. Sybille Bammer, Austria, 6-1, 7-6 (2).
Daniela Hantuchova (2), Slovakia, def. Carla Suarez Navarro, Spain, 6-4, 6-3.