BERLIN, July 15 (Xinhua) -- Top seeded Nikolay Davydenko of Russia was upset by Daniel Gimeno-Traver of Spain 7-6 (7), 2-6, 6-1 in the second round of the Mercedes Cup in Stuttgart on Thursday.

The Russian world number six struggled to find his best shape in the opening set, failing to prevail when facing the 88th ranked Gimeno-Traver. After the two players tied 6-6 to reach the tiebreaker, Davydenko concede the close set in 7-9.

In the second set the Russian seemed to control the rhythm on the court, winning 6-2 to even the score. However, the unseeded Gimeno-Traver refused to be rallied past. Thanks to his aggressive serves with a dozen of aces, the Spaniard shocked Davydenko 6-1 to seal the victory.

Gimeno-Traver will face Swiss Marco Chiudinelli on Friday in the third round of the Mercedes Cup, a 450,000-dollar ATP event on clay at the TC Weissenhof.