Valencia - Gilles Simon's bid for a berth at the World Tour Finals suffered a setback when the French fifth seed was beaten 6-4, 4-6, 6-3 by Russian former world No 3 Nikolay Davydenko in the first round of the Valencia Open on Monday.
Davydenko, who has slipped to 36th in the rankings and is unseeded for the Spanish hard-court event, had lost five in a row against the world No 12 but broke Simon four times and lost his own service only twice to set up victory.
The 30-year-old will play the winner of Monday's match between French qualifier Nicolas Mahut and unseeded Spaniard Guillermo Garcia-Lopez.
Simon has only the Paris Masters left to try to secure a spot at the season-ending finals in London starting on November 20.
Top seed and defending champion David Ferrer of Spain takes on unseeded compatriot Fernando Verdasco in the pick of Tuesday's first-round action.
World No 5 Ferrer has already qualified for the eight-man London finals along with Novak Djokovic, Rafael Nadal, Andy Murray and Roger Federer.
Czech Tomas Berdych, Jo-Wilfried Tsonga, who is playing in Valencia, and American Mardy Fish currently occupy the next three spots in the race to secure a place in the season finale.
Results on Monday from the Valencia Open (seedings in parentheses):
Nikolay Davydenko, Russia, def. Gilles Simon (5), France, 6-4, 4-6, 6-3.
Fabio Fognini, Italy, def. Daniel Gimeno-Traver, Spain, 6-4, 6-3.
Nicolas Mahut, France, def. Guillermo Garcia-Lopez, Spain, 7-6 (7/5), 6-2.
Vasek Pospisil, Canada, def. John Isner, United States, 6-3, 3-6, 7-6 (11/9).