Juan Martin del Potro closed in on a World Tour Finals place by beating Robin Haase 7-5, 6-4 in the Paris Masters last-16 on Thursday.
The former US Open champion can take the eighth and final qualification spot for London from Pablo Carreno Busta if he reaches the semifinals at here.
The 13th-seeded Argentine had little trouble in seeing off Haase, who had notched up his first win over a top-5 player by beating Alexander Zverev on Wednesday.
Three successive breaks of serve left del Potro serving for the first set, which he took on his fourth set point. The 29-year-old grabbed the crucial break in the fifth game of the second set, before closing out a comfortable victory.
del Potro, who was 47th in the ‘Race to London’ standings before the US Open, is now one win away from reaching his fifth semifinal in six events.
If del Potro reaches the semifinals, Lucas Pouille would have to win the tournament to deny him a spot at the year-ending eight-man event.
The results: Third round: Juan Martin del Potro bt Robin Haase 7-5, 6-4; Fernando Verdasco bt Dominic Theim 6-4, 6-4; Filip Krajinivic bt Nicolas Mahut 6-2, 3-6, 6-1.
Second round: Julien Benneteau bt Jo-Wilfried Tsonga 2-6, 7-6(4), 6-2 .
