Kateryna Bondarenko caused the upset of the tournament at the Japan Women's Open Tennis on Tuesday, defeating number one seed Carla Suarez Navarro 6-4, 6-4. With this win, the Ukrainian has been has continued her great form this summer, qualifying for Istanbul, Cincinnati, Stanford and the U.S. Open, and defeating Venus Williams along the way. For Suarez Navarro, this is her eighth loss in a row. After not having won a match since playing on the grass of Birmingham nearly three months ago, it is a worrying time for the Spaniard.

Bondarenko takes topsy-turvy opening set

The match began with both players holding their opening service game, respectively. But at one-all, Suarez Navarro began to force the issue on Bondarenko's serve, and was rewarded with a break of serve. Now up 2-1, the number one seed looked to be on her way to another routine service hold but some costly errors gave Bondarenko the break straight back. From there, both women looked to be getting more and more comfortable on serve after trading breaks. However, trailing 3-4 and serving, a number of unforced errors flew off of the Spanish number two's racquet, handing her Ukrainian counterpart another break of serve and a chance to serve for the set.

Bondarenko had two set points in the next game but was unable to convert any of them, and Suarez Navarro's experience began to show. Ultimately, it was the world number 12 who was able to break back, prolonging the set for at least, another game. Now trailing 4-5, the number one seed held a 40-0 lead on her own serve but she was unable to use any of her chances. In the end, Bondarenko was able to convert her fourth set point to take the opening set 6-4.

Crucial hold of serve in set number two was enough to secure Bondarenko the win

The second set began much like the first but this time, both women held their serve twice before the first break of serve presented itself. At two games apiece with Bondarenko serving, Suarez Navarro only needed one break point to edge in front, with a 3-2 lead. That lead, just like in the opening set, was quickly diminished as a slew of unforced errors from the Spaniard and some great play from the Ukrainian was enough to give Bondarenko the break right back.

The world number 85 looked like she had found her groove again and managed to hold her serve to go up a 4-3 lead. In the next game, Suarez Navarro's woes on serve continued as she was broken once more, and Bondarenko had a chance to serve for the match. Now with her back against the wall, the number one seed desperately needed a break of serve, and she got one.

Four nervous-looking errors off of the Ukrainian's racquet was enough to hand the Spaniard the break back. Despite getting a short lifeline back into this match, Suarez Navarro was unable to capitalize and her unforced errors tally continued to pile up in the tenth and final game of the second set. On her first match point, Bondarenko hit a blistering backhand winner down the line to seal a 6-4, 6-4 win over the number one seed. In the next round, the world number 85 will face Australia's Jarmila Gajdosova, who beat Russia's Alexandra Panova in straight sets.