Rafael Nadal stayed on course to finish the year as number one after he saw off Jo-Wilfried Tsonga 7-6 (7-4) 6-1 to reach the Paris Masters semi-finals.
The Spanish 19-time Grand Slam singles winner, who now faces Denis Shapovalov, needs to win the event to guarantee top spot heading into 2020.
Earlier, number one seed Novak Djokovic thrashed Stefanos Tsitsipas 6-1 6-2.
He will face Grigor Dimitrov on Saturday after the Bulgarian defeated Chile's Cristian Garin 6-2 7-5.
Djokovic, winner of 16 Grand Slams, took only 58 minutes to overcome the Greek player.
The Serb, who will lose his number one ranking to Nadal next week, said: "I played one of the best matches of the season.