Kevin Anderson and Jo-Wilfried Tsonga are no longer in ATP Finals contention after second-round defeats at the Paris Masters, where David Goffin edged towards an appearance in London.
The race for the end-of-season showpiece event is in its final week as the likes of Goffin, Pablo Carreno Busta and Juan Martin del Potro battle it out for the two remaining spots.
Lucas Pouille, Roberto Bautista Agut, John Isner and Jack Sock also remain in the picture after their wins on Wednesday, although their chances depend on the fortunes of others.
Meanwhile, the faint hopes of Diego Schwartzman and Albert Ramos-Vinolas were extinguished - the former beaten in three sets by Isner while the Spaniard also lost over the full distance to Pablo Cuevas.
Three men already assured of their spots - Rafael Nadal, Grigor Dimitrov and Marin Cilic - all won, the Spaniard securing the year-ending number-one ranking thanks to his 7-5 6-3 success over Chung Hyeon.
GOFFIN ONE WIN AWAY
The Belgian only needs to reach the last eight in Paris to secure his Finals berth, and Julien Benneteau stands in his way.
Goffin needed three sets to oust Adrian Mannarino on Wednesday, advancing 6-2 2-6 6-3. The world number 10 fell 2-0 behind in the opener but reeled off six straight games to get ahead, only for Benneteau to break twice in the second and level.
The crucial breakthrough in the decider went Goffin's way, though, and he was dominant on serve from then on to ease into the third round.
TSONGA AND ANDERSON FALL BY THE WAYSIDE
There will be no Finals outing for US Open runner-up Anderson, who lost 5-7 6-4 7-5 to Fernando Verdasco.
It looked as though the deciding set was heading for a tie-break only for Verdasco to break the South African to love for a 6-5 lead. Anderson did force a break-back opportunity but the Spaniard held and converted his second match point.
Tsonga, meanwhile, was ousted by his compatriot Benneteau, who fought back from losing the opening set to prevail 2-6 7-6 (7-4) 6-2.
HAASE ON A ROLL
There was a shock as fourth seed Alexander Zverev, winner of Masters titles in Montreal and Rome this year, was consigned to a 3-6 6-2 6-2 defeat by world number 43 Robin Haase.
Dutchman Haase hammered Steve Johnson 6-2 6-1 in the first round and followed that ruthless performance up with a shock win over world number four Zverev.
Haase claimed four breaks and won 77 per cent of points on serve, losing just two points behind his serve in the final set to move into round three. Zverev must now regroup ahead of his Finals debut at the O2 Arena.
PERMUTATIONS, QUALIFICATIONS AND COMPLICATIONS
While Goffin's route to London is straightforward, the same cannot be said for a number of his rivals. Carreno Busta occupies the eighth spot but he was dumped out in the first round in Paris by Nicolas Mahut.
Del Potro, who saw off Joao Sousa 6-2 6-2 on Wednesday, can overtake Carreno Busta if he makes the last four. Pouille, a straight-sets winner against Feliciano Lopez, must reach the final to give himself a chance.
Bautista Agut romped past Jeremy Chardy 6-4 6-1 while Sock produced a stunning fightback from 5-1 down in the decider to overcome Kyle Edmund. That pair, along with Isner, need to lift the trophy to have any hope of qualification.