Spaniard Fernando Verdasco overcame a sluggish start to beat Marin Cilic 3-6, 6-2, 6-3 at the Paris Masters on Monday and set up a second round meeting with Tomas Berdych.
World No 23 Verdasco needed a set to adjust to Cilic's big serve before easing past his Croatian opponent in front of a sparse audience at Bercy.
Seven players taking part in the Paris tournament are vying to clinch one of the three remaining spots for the November 20-27 finals at the O2 Arena.
Cilic converted his only break point to wrap up the first set but Verdasco broke in the second game of the second set, then held serve to level the match.
After that he never looked back.
Local favourite Nicolas Mahut pleased the crowd with a comprehensive 6-2 6-3 win over Spaniard Juan Carlos Ferrero.
On Tuesday, London hopeful Jo-Wilfried Tsonga of France, the sixth seed, will take on Spain's Guillermo Garcia-Lopez.
Tsonga will also definitely qualify for London by reaching the quarter-finals, as will American Mardy Fish.
World No one Novak Djokovic tops the draw with Briton's Andy Murray seeded two in the absence of Rafa Nadal.
Tsonga loses opening match in Shanghai
Wozniacki falls as Ivanovic joins China Open casualty list
Cilic outserves Ljubicic to reach China final
Berdych beats Cilic to win China Open
Germany's Mayer stuns Nadal, Murray marches on