Russian Nikolay Davydenko outslugged Argentine Juan Martin Del Potro 6-3, 6-2 in a winner-takes-all battle for a place in the semi-final of the Masters Cup on Thursday.
The 27-year-old world number five joined Novak Djokovic and Andy Murray in the last four, reaching the knockout stage for the second time in four appearances at the season finale for the top eight players in the world.
Defending champion Roger Federer must beat Briton Murray on Friday to claim the final place in the last four, which will otherwise go to Frenchman Gilles Simon.
Del Potro, who now heads home for next week's Davis Cup final against Spain, held his own through some long early rallies but once he lost the first set, the long season and a toe injury looked to have caught up with him and he folded.
Jo-Wilfried Tsonga earlier restored some pride by coming back from a set down to beat world number three Djokovic 1-6, 7-5, 6-1 in a dead rubber match in the same Gold Group.
The Frenchman had lost his first two matches at the $4.45 million tournament and looked on his way to a third defeat when Djokovic, who had already won the Gold Group, took the first set in 25 minutes.
Tsonga, who had beaten Djokovic to win his first title in Bangkok in September and again on his way to winning the Paris Masters, broke the 21-year-old Serbian to even the match up before prevailing in a third set as one-sided as the first.
The 23-year-old Tsonga, who lost to Djokovic in the final of the Australian Open, said he was nevertheless delighted with a season when he broke into the world top 10 despite playing just 15 tournaments and had knee surgery in May.
"For me it's just very good to have years like this," he said. "With all my problems I played very well. I hope to play better next year. I'm very happy with this year."
