Jo-Wilfried Tsonga of France strengthened his bid for a spot in the ATP finals by beating Japan's Kei Nishikori 7-6 (5), 6-0 Thursday to advance to the Shanghai Masters quarterfinals.
Juan Martin del Potro also advanced when 11th-seeded Tommy Haas withdrew before their match with a back injury.
Tsonga and del Potro are among a group of players trying to snag the final five spots in the year-end championships in London next month.
Tsonga is currently two spots out of the eight-man field, needing a strong run in Shanghai and the Paris Masters at the end of October to qualify.
Del Potro is in fifth place and the Argentine can wrap up his spot by reaching the Shanghai final.