French teenager Prithika Pavade, 16, overcome Matelova 7-11, 11-5, 12-10, 11-7, 7-11, 11-9 in a six-game thriller in Guimarães in Portugal.

Second seed Barbora Balazova was also knocked out at the last 16 stage by French opposition as ninth seeded Yuan Jia Nan claimed a 18-16, 10-12, 11-8, 11-9, 7-11, 11-9 triumph.

There was better news for the third and fourth seeds as Russia’s Yana Noskova and Portugal’s Shao Jieni came through their respective encounters in four games.

Noskova defeated Belarus’ Daria Trigolos 11-8, 11-7, 11-7, 11-6, while Shao saw off Bulgaria’s Polina Trifonova 11-6, 11-6, 11-8, 11-7.

Ukraine’s Solomiya Brateyko upstaged her higher seeded opponent as the number 28 seed fought back from two games down to beat Italy’s Giorgia Piccolin, seeded 11 positions higher, 6-11, 8-11, 11-7, 11-9, 11-5, 11-9.

Spain’s Maria Xiao, Britain’s Charlotte Carey and Sweden’s Christina Källberg also progressed to the quarter-finals.

Pavade booked her place in the semi-finals with a 11-5, 11-7, 4-11, 11-5, 11-7 win and will next face Noskova who overcame Källberg 11-7, 12-14, 11-6, 11-3, 6-11, 8-11, 11-4.

Shao will meet Yuan in the other semi-final contest after they defeated Carey 11-6, 10-12, 11-5, 12-10, 9-11, 7-11, 13-11 and Xiao 16-14, 11-6, 11-7, 11-5 respectively.

There were also upsets in the men’s singles draw as Austria’s Daniel Habesohn, who started the day as the highest seeded player, lost 11-13, 11-9, 11-8, 11-6, 11-8 to Romanian number 20 seed Rares Sipos.

Unlike the women’s event, there was no last 16 elimination for the second seeded player as Czech Republic’s Pavel Sirucek held strong against Luxembourg’s Eric Glo to win 15-13, 11-5, 11-6, 6-11, 12-10.

Fourth seed Kou Lei of Ukraine brushed aside Belgian number 10 seed Cedric Nuytinck with a 14-12, 11-8, 11-8, 14-12 triumph.

Greece’s Panagiotis Gionis, seeded third, suffered a 2-11, 11-9, 7-11, 11-9, 9-11, 12-10, 11-6 defeat at the hands of Spain’s Alvaro Robles.

Elsewhere, young Russian talent Vladimir Sidorenko impressed in his 11-3, 11-9, 14-12, 11-6 victory over Slovakian ninth seed Lubomir Pistej, while Britain’s Paul Drinkhall, Denmark’s Tobias Rasmussen and Poland’s Samuel Kulczycki advanced to the next round.

Sipos then secured his place in the last four after thrashing Rasmussen 11-4, 13-11, 11-7, 11-6.

Kou will be his next opponent after the Ukrainian downed Kulczycki 11-9, 11-5, 11-5, 15-13 in the quarter-finals.