Maria Sharapova brushed aside Klara Koukalova 6-1, 6-2 in the first round of the Madrid Open, while Ana Ivanovic beat Madison Keys 6-1, 7-6.
Sharapova, who lost to Serena Williams in last year's final, converted six of eight break points to take advantage of Koukalova's eight double-faults on the Caja Magica clay court.
The eighth-seed Russian will play Christina McHale of the United States in the second round.
Meanwhile, 11th-seeded Ivanovic ousted Keys to set up a meeting with fellow Serb Bojana Jovanovski.
Top-ranked Williams opens her title defence later against Swiss Belinda Bencic.