TAIPEI, Taiwan - No.1 seed Danka Kovinic made straightforward progress in the Taipei OEC Open with a 6-2, 7-5 victory over Urszula Radwanska.

The Montenegro player won the opening set in 41 minutes before being stretched in the second, which took over an hour.

Kovinic was the first to face a break point but after staving it off in the third game immediately took the ascendancy in the match as she broke to love. Her serve would never seriously be threatened as she closed out the opening set by breaking once more.

The second proved a far more testing affair. Indeed, the Pole broke in the opening game, held and then established a 0-40 lead that could have given her a double break advantage.

Kovinic, though, salvaged the situation and quickly re-established herself on level terms. From there, the players held serve in five successive games, leaving Radwanska to serve to stay in the match.

A tight game went the way of the top seed, who set up a quarterfinal meeting with Kyoka Okamura, who defeated Isabella Shinikova, 1-6, 6-2, 6-4, in a three setter that lasted only 85 minutes.

No.3 seed Vitalia Diatchenko also remains in the top half of the draw following a 6-4, 6-4 triumph over Kamilla Rakhimova.

In the lower half of the draw, No.2 seed Timea Babos was stretched by Storm Sanders, the WTA World No.424 but came out on top, 6-4, 7-6(10).

She seemed on course for a routine win as she served for the match at 5-4 in the second set but missed but, having missed two match points in the previous game, was broken and forced into a tense tiebreak.

Babos saved two set points during the breaker and missed two further match points of her own before finally sealing the win.

Dalila Jakupovic took a couple of hours exactly to see off the challenge of France’s Amandine Hesse, 3-6, 6-3, 6-3, while Kaja Juvan, the No.6 seed, was forced to retire when leading Naiktha Bains, 6-1, 2-6, 4-3.

Viktoriya Tomova, the No.8 seed, was Wednesday’s other winner as she defeated Yang Ya Yi, 6-4, 6-2.

Happy retirement, Dominika Cibulkova!