Petra Kvitova coasted into the semi-finals of the Prague Open with a routine win over Katerina Siniakova, but there was disappointment for fellow Czech Kristyna Pliskova.

Second seed Kvitova, making her first appearance in the tournament since its elevation from ITF to WTA status, needed a little over 70 minutes to record a 6-3 6-3 triumph against her compatriot.

Siniakova actually broke her opponent in the opening game of the match, but that was about as good as things got for the eighth seed, as Kvitova earned five breaks of serve herself on the back of 21 winners.

Awaiting in the semi-finals is sixth seed Zhang Shuai, who overcame the challenge of Jasmine Paolini in a 6-4 6-3 triumph.

On the other side of the draw, Pliskova was ousted by seventh seed Mihaela Buzarnescu in a 6-2 6-3 defeat.

Buzarnescu reached the final in Hobart in January, but has largely struggled for consistency before this week, where she has made the last four without dropping a set.

Camila Giorgi stands between Buzarnescu and the final, the Italian having defeated Sam Stosur 6-2 6-3.

At the Grand Prix de SAR La Princesse Lalla Meryem, top seed Elise Mertens outclassed Sara Errani in a 6-3 6-1 win to set up a semi-final meeting with Hsieh Su-wei, who hammered Katarina Zavatska 6-1 6-1.

Seventh seed Ana Krunic was leading 6-2 1-0 against Paula Badosa Gibert before her opponent retired with injury.

Ajla Tomljanovic had a more difficult route to the last four, fighting back from a set down against Jana Fett to win 3-6 6-3 6-3.