The opening day of action at the inaugural Ladies Open Biel Bienne saw two seeds tumble out in round one.

Fourth seed Roberta Vinci was beaten 6-4 6-4 by Kristyna Pliskova at the hard-court event, a solitary break in each set proving decisive for the Czech.

And the next match saw Monica Niculescu, the eighth seed in Switzerland, win only four games as she was trounced by Belgian youngster Elise Mertens.

Mertens dominated proceedings to claim a 6-2 6-2 win in an hour and 22 minutes.

There were also straight-sets victories on Monday for Mona Barthel and Annika Beck.

Top seed Barbora Strycova will begin her campaign on Tuesday, against qualifier and fellow Czech Marie Bouzkova.