MADRID (AP) — Second-seeded Angelique Kerber lost 6-4, 6-2 to Barbora Strycova in the first round of the Madrid Open on Sunday.

Heading into their clay-court opener, this year's Australian Open champion hadn't dropped a single set to Strycova in four prior meetings.

But the third-ranked Kerber committed three double faults and was broken by Strycova four times to fall in a little over an hour.

The 33rd-ranked Strycova will face Madison Keys in the second round after she rallied past fellow American Alison Riske 1-6, 6-3, 6-4.

Also, seventh-seeded Roberta Vinci lost 6-4, 6-2 to Danka Kovinic, while 13th-seeded Karolina Pliskova brushed off Lourdes Dominguez Lino 6-2, 6-1.

Kovinic hit six aces and broke Vinci four times.