April 16 (Reuters) - Top two seeds Elena ⁠Rybakina and Coco Gauff marched into the quarter-finals of the Stuttgart Open with straight-sets wins on ⁠Thursday, as Mirra Andreeva set up a last-eight clash with Wimbledon champion Iga Swiatek.

Australian Open ‌champion Rybakina beat Diana Shnaider 6-3 6-4, while Gauff overpowered Liudmila Samsonova 7-5 6-1, after Andreeva beat Alycia Parks 7-6(3) 6-3.

World number two Rybakina put on a clinical display, never facing a break point on her own serve and landing nine aces while ​Shnaider could manage only one.

"Happy with the win, definitely, but still ⁠a lot to improve," Kazakhstan's Rybakina said ⁠after her first claycourt match of the year.

American Gauff, also playing her first match on clay this ⁠season, ‌got broken twice as Samsonova took a 3-0 lead in the first set, but the world number three bounced back to win the next four games. Samsonova broke again to go 5-4 ⁠up but Gauff won the next three games to win the ​set.

A confident Gauff won five games ‌straight in the second set to set up a last-eight clash with Karolina Muchova.

"It's a ⁠surface where I love ​and hate it," Gauff said about playing on clay.