In the women's draw, Dominika Cibulkova lost 6-4, 6-4 to Garbine Muguruza. Simona Halep defeated Lesia Tsurenko 6-3, 6-1 to set up a semifinal with Carla Suarez Navarro, who rallied past Tsvetana Pironkova 2-6, 6-4, 6-4.
Wawrinka lost his service in the first game of the second set before Chardy reeled off three straight service games at love to reach 5-3.
Wawrinka broke back and easily won the tiebreaker. He'll play Guillermo Garcia-Lopez in the semifinals Friday after the Spaniard beat Jan Hernych 6-4, 6-1.
Kirsten Flipkens overcame a sore back to stop last year's finalist Urszula Radwanska 6-4, 6-4. She'll play Muguruza in the semifinal.
Flipkens was up 3-2 in the second set when she called for a medical timeout and received treatment on her back.