Valencia - France's Jo-Wilfried Tsonga suffered a blow in his bid to seal a berth in the ATP World Tour finals on Thursday when he crashed 7-6 (7/5), 6-2 in the second round of the Valencia Open to 116th-ranked American Sam Querrey.
The defeat is a severe blow to Tsonga's chances of taking one of the three remaining berths for the eight-man finals to be staged in London from November 20-27.
Tsonga, who won their only previous meeting in Shanghai last year, missed the chance to leapfrog Czech Tomas Berdych and become No 6 on the ATP rankings.
The 26-year-old Frenchman will now attempt to clinch one of the remaining berths at the Paris Masters where he won the title in 2008.
Querrey will now face the winner of Argentine Juan Martin Del Potro or South Africa's Kevin Anderson in Friday's quarter-final.
Argentina's Juan Monaco also advanced in straight sets, beating Italy's Fabio Fognini 6-3, 6-1 in their second round tie.