Defending champion Serena Williams swept the last six games to overhaul Ana Ivanovic 3-6 6-4 6-2 in the quarter-finals of the Cincinnati Masters.

Her next opponent will be Ukrainian 14th seed Elina Svitolina, who upset Roland Garros finalist Lucie Safarova 6-4 2-6 6-0.

Williams said that after playing on the back foot in the first set, she raised her game to post her ninth victory in ten meetings over the former Roland Garros champion from Serbia.

“I was lethargic in the first set and she played incredibly well. I just had to do better,” Williams said of the clash, a repeat of the 2014 Cincinnati final won by the American.

“This was my best performance since (winning) Wimbledon. I hope to take the momentum into the next match.”

The last two women’s semi-finalists will be decided as third seed Simona Halep plays Russian Anastasia Pavlyuchenkova and former winner Jelena Jankovic faces Anna Schmiedlova of Slovakia.