Carla Suarez Navarro through to quarter-finals in Strasbourg

Number four seed Carla Suarez Navarro moved into the quarter-finals of the Internationaux de Strasbourg with a straight sets win over American Christina McHale.

After top seed Caroline Wozniacki withdrew on Monday because of back trouble and number two seed Elena Vesnina then lost her first-round match to qualifier Camila Giorgi, the Spanish world number 22 produced a composed display to see off McHale 6-4 6-1 in one hour and 28 minutes.

Australian Samantha Stosur secured her place in the last eight and a date with Suarez Navarro after she beat Madison Brengle of the United States 6-0 6-1.

China's eighth seed Shuai Peng defeated Frenchwoman Amandine Hesse 7-5 6-2 but Puerto Rican ninth seed Monica Puig is out following her 6-2 6-3 loss against Czech player Kristyna Pliskova.

At the Versicherungs Cup in Nuremberg, b oth top seeds Kiki Bertens and Yulia Putintseva progressed into the second round.

Bertens saw off Germany's Katharina Gerlach 6-2 6-1 while Putintseva came through 6-4 5-7 6-0 against Julia Glushko.

Number four seed Laura Siegemund beat fellow German Katharina Hobgarski 6-0 6-1.

In Tuesday's second round matches, fifth seed Alison Riske progressed to quarter-finals as the American defeated Belgium's Kirsten Flipkens 6-2 6-2 to set up a potential showdown with Bertens.

Sorana Cirstea battled past Varvara Lepchenko 6-0 6-7 (4/7) 6-3 and could meet Putintseva if she also goes on to reach the last eight.