Second seed Petra Kvitova claimed her place in the second round of the J&T Banka Prague Open with a comfortable win over wildcard Tereza Smitkova.
The world number 10, who is the highest-ranked player in the tournament following the withdrawal of top seed Karolina Pliskova, overcame her fellow Czech 6-1 6-3.
Kvitova won nine consecutive games at one point in a dominant display, although she did suffer a brief lapse to have her serve broken in the second set.
It did not prove a serious setback, with Kvitova breaking back and then holding out for victory.
Another Czech, the fifth-seeded Barbora Strycova, saw her hopes come to an end as she was beaten 6-0 2-6 6-2 by Italy's Camila Giorgi.
Third seed Daria Kataskina also suffered defeat, losing 7-6 6-3 to Jasmine Paolini of Italy.
Belgium's Elise Mertens made a convincing start at the Grand Prix De SAR La Princesse Lalla Meryem in Rabat with a 6-0 6-0 victory over Kristina Kucova.
Mertens, the top seed and world number 19, saw off the Slovakian in 56 minutes.
Second seed Dominika Cibulkova of Slovakia did not enjoy such joy, losing 2-6 7-5 6-4 to Slovenia's Polona Hercog.
Former world number five Sara Errani, French Open finalist in 2012, beat sixth seed Zarina Diyas 6-4 6-4.