GSTAAD, Switzerland - Estonia's Anett Kontaveit won a battle of young stars on Wednesday, edging past Russian teenager Anna Kalinskaya, 6-4, 4-6, 6-4 to reach the quarterfinals of the Ladies Championship Gstaad.

"I felt like I started off really well and then she got into the match more. It got really close from there," Kontaveit said after the match.

Kontaveit has enjoyed a stellar rise up the WTA rankings after solid results on all surfaces - including her first title in 's-Hertogenbosch - but was up against tough opposition in the 18-year-old.

Kalinskaya is a former junior French Open finalist and earned her first Top 30 win over Caroline Garcia earlier this season at the Alya Malaysian Open.

The 21-year-old Kontaveit nonetheless fended off a surging Kalinskaya to take the opening set after leading 5-2, but fell behind a break to start the second.

"She managed to serve well to win the second set. I got the break in the beginning of the third, but played a so-so service game to lose it. It was just holding serve from there."

Holding on for dear life, Kalinskaya leveled the match on her second set point and survived an early exchange of breaks in the decider to put herself within two games of the upset.

Kontaveit's 2017 improvements were put to the test but passed with flying colors, holding to love and clinching victory on her first match point after one hour and 53 minutes on court.

"I played really well in the last game to break her. I’m really happy to be in the quarterfinals; it was a really tough match."

It was a seamless serving day for the Estonian, who struck 10 aces and won 73% of her first serve points, and will play the winner of the second round encounter between No.6 seed Carina Witthoeft and Rebecca Sramkova.

"I’ve played Witthoeft before but the conditions are different here and it’s a new match, so I don’t think it really matters.

"Previous results don’t matter much to me; I just take it as it comes. Whoever I play, I try to fight."