'S-HERTOGENBOSCH, Netherlands - Playing just her second WTA main draw, qualifier Veronika Kudermetova caused a shock on the second day of the Libéma Open, ousting defending champion and No.4 seed Anett Kontaveit 6-4, 7-6(4) in the first round.

For the second edition in a row, the previous year's 's-Hertogenbosch winner has lost their opening match: last year, 2016 winner CoCo Vandeweghe was stunned 6-7(3), 6-3, 7-5 by Carina Witthoeft. And although Kudermetova is a very new face to Tour level, the 21-year-old is already garnering a reputation as a giant-killer: she has now defeated a Top 30 opponent in the first round both times she has come through qualifying following her upset of Carla Suárez Navarro in Stuttgart this April. Indeed, this is the Russian's second win in as many meetings over Kontaveit - having defeated her in the first round of the Moscow ITF $25,000 event in 2015 by a scoreline of 6-3, 6-2 as well.

Kontaveit, perched at a career high ranking of No.24 following a brilliant clay season in which the Estonian notched up semifinals in Stuttgart and Rome before defeating Petra Kvitova to make the fourth round of Roland Garros, would seem to have been perfectly poised to translate her power game to grass. But it was the World No.170 whose own booming serve was clicking today as Kudermetova fired down nine aces to Kontaveit's six.

An evenly contested first set saw the Russian fend off break points in an early tussle on serve - and thereafter hold comfortably, while snatching her first opportunity on the Kontaveit serve in the ninth game. The same pattern held in the second set - but this time, when Kudermetova was unable to convert three match points while attempting to serve for a career-best win, there was a rather more dramatic finish.

When Kontaveit, having broken back for 5-5 with some big hitting and unrestrained returns, staved off four break points to move up 6-5, it seemed as though the momentum had shifted to the 22-year-old. But an unfazed Kudermetova gathered herself and, coming up with some of her best serves under pressure, powered through 11 of the next 15 points - sealing the match with a service winner. The Russian will next bid to make her maiden quarterfinal against either Belinda Bencic or lucky loser Tereza Martincova.