Top-seeded Janko Tipsarevic upset by Argentine qualifier Guido Pella in Duesseldorf
{{#rendered}} {{/rendered}}Argentine's Guido Pella returns a shot to Serbia's Janko Tipsarevic during their tennis match at the Power Horse Cup in Duesseldorf, Germany, Wednesday, May 22, 2013. Pella, a qualifier, defeated top seeded Tipsarevic with 7-6 and 6-1. (AP Photo/dpa, Caroline Seidel) (The Associated Press)
Top-seeded Janko Tipsarevic lost in the second round of the Power Horse Cup on Wednesday, falling 7-6 (1), 6-1 to Argentine qualifier Guido Pella.
It's the biggest career win for the 101st-ranked Pella, knocking out the 10th-ranked Serb to reach the ATP World Tour quarterfinals for the first time.
Pella will play seventh-seeded Viktor Troicki of Serbia, who defeated Grega Zemlja of Slovenia 6-3, 7-6 (3).
{{#rendered}} {{/rendered}}Third-seeded Juan Monaco of Argentina topped Andre Ghem 6-4, 6-4 of Brazil to set up a quarterfinal with Tobias Kamke, who beat Aljaz Bedene 6-1, 6-4.
Second-seeded Tommy Haas of Germany rallied past Ivan Dodig 3-6, 6-4, 7-5.