Wang through in Prague, easy for Mertens in Rabat
Wang Qiang and Elise Mertens each triumphed in their respective tournaments on a day of few shocks on the WTA Tour.
World number 16 Wang was in action at the Prague Open and was pushed to three sets by Mandy Minella but ultimately emerged victorious, winning 6-1 4-6 6-4.
A clash with Bernarda Pera, who defeated Antonia Lottner in straight sets, awaits the third seed in the last eight.
There will be at least one home representative in the last four after Czech seeds Barbora Strycova and Katerina Sinakova eased through to set up a quarter-final meeting.
Fellow home favourite Karolina Muchova is also into the next round, along with Natalia Vikhlyantseva, Jil Teichmann and Tamara Korpatsch.
At the Grand Prix de Sar la Princesse Lalla Meryem in Rabat, Mertens raced through 6-4 6-0 against Ivana Jorovic.
The seeds were untouchable in Morocco, too, although Hsieh Su-wei had to come from behind to defeat Lara Arruabarrena 4-6 7-5 6-3.
Ajla Tomljanovic and Johanna Konta also needed three sets to win, but Maria Sakkari defeated Isabella Shinikova in straight sets, while Alison van Uytvanck did likewise against Varvara Lepchenko, dropping just four games.
Rebecca Peterson and Ysaline Bonaventure complete the quarter-final draw.