American Taylor Fritz became the fifth player to book his spot in the eight-man ATP Finals in Turin after last week's Paris Masters.
Fritz joins already-qualified Jannik Sinner, Alexander Zverev, Carlos Alcaraz and Daniil Medvedev for the event in northern Italy from 10-17 November.
Novak Djokovic, the two-time ATP Finals defending champion, missed the Paris Masters but remains in the running in sixth spot.
Fritz, 27, was eliminated in the second round in Paris by British No 1 Jack Draper.
Four players are chasing the three remaining berths – Djokovic, Casper Ruud, Alex de Minaur and Andrey Rublev.
Ruud and Rublev are playing in Metz, France this week, with De Minaur in action in Belgrade, to try to get ahead of Djokovic, who is not playing this week.