ISTANBUL (REUTERS) - Caroline Wozniacki was made to work hard for a victory at the Istanbul Cup on Thursday (April 26), coming from behind to beat Sara Errani 5-7 6-3 6-3 and reach the quarter-finals.

After losing a tight opening set, world number two Wozniacki pulled herself back into the match before switching gears in the decider to secure victory in two hours and 26 minutes.

The Australian Open champion fired 47 winners to Errani's 23 and broke the Italian six times to set up a meeting with France's Pauline Parmentier.

Also advancing to the quarter-finals was Maria Sakkari who eased past Aleksandra Krunic 6-3 6-1. She was joined by Arantxa Rus of the Netherlands who came through a tough three-setter against Danka Kovinic.

Slovenia's Polona Hercog progressed to the last eight after her opponent Kateryna Bondarenko pulled out of their match due to injury. Hercog was ahead 6-2 1-1 when Ukraine's Bondarenko retired.

Donna Vekic overcame Australia's Ajla Tomljanovic 6-1 6-2 and takes on Irina-Camelia Begu in the quarter-finals.