Novak Djokovic put Serbia into the inaugural ATP Cup final as they beat Russia 3-0 in Sydney.
The world number two overcame US Open finalist Daniil Medvedev 6-1 5-7 6-4 to give Serbia an unassailable 2-0 lead.
Dusan Lajovic had earlier beaten world number 17 Karen Khachanov 7-5 7-6 (7-1) before Viktor Troicki and Nikola Cacic made it a clean sweep in the doubles.
Serbia will play either Spain or Australia in Sunday’s final.
“Medvedev is one of the best players in the world and he showed today why,” Djokovic said after their rubber.
“This was the most difficult challenge I have had so far this year.”
The 19-time Grand Slam champion later withdrew from the ATP event in Adelaide, which begins on 12 January. The Australian Open – the first Grand Slam of the year – starts on 20 January.