Top seeded Roberta Vinci of Italy eased past Portuguese wildcard Maria Joao Koehler 6-2, 6-0 to reach the quarter-finals of Estoril Open on Wednesday.

Fourth seeded Czech Petra Cetkovska defeated Heather Watson of Britain 6-3, 6-1 and sixth seeded Kaia Kanepi battled past American Vania King 6-3, 6-4.

"The conditions were very tough and we had a lot of long rallies, and I'm happy I could win today," Kanepi said. "I'm feeling very well and healthy right now. It's my third clay court tournament and I feel like I'm improving every match."

Italian qualifier Karin Knapp scored the upset of the day with a 1-6, 6-1, 7-5 victory over second seeded Russian Maria Kirilenko.

Third seeded Anna-Lena Groenefeld was also shown the exit door by Sílvia Soler-Espinosa in all-Spanish clash with 3-6, 6-3, 7-5 victory.

"It was our first time playing and it was really tough," said Soler-Espinosa .

"She plays really well on clay and was playing a lot of spin to my backhand. She was doing it really well in the first set. But at the end I was able to get to my forehand more"