Valencia - Gael Monfils's bid for a berth at this month's World Tour finals suffered a setback when the third seed was upset 7-6 3-6 6-4 by unseeded Spaniard Marcel Granollers in the quarter-finals of the Valencia Open on Friday.
Frenchman Monfils must now win the Paris Masters, where he has twice finished runner-up, to secure one of three remaining places in the eight-man, season-ending competition at London's O2 Arena.
Argentina's Juan Martin Del Potro, the sixth seed, will try to boost his attempt to claim a London spot later on Friday when he plays unseeded American Sam Querrey.
Friday's two remaining quarter-finals feature top seed and defending champion David Ferrer against Nikolay Davydenko and former world number one Juan Carlos Ferrero against Argentine wildcard Juan Monaco.
Spaniard Ferrer, the world number five, has already qualified for the Nov. 20-27 finals along with Novak Djokovic, Rafa Nadal, Andy Murray and Roger Federer
Marcel Granollers, Spain, def. Gael Monfils (3), France, 7-6 (12), 3-6, 6-4.
Juan Martin del Potro (6), Argentina, def. Sam Querrey, United States, 6-2, 7-5.