Rafael Nadal came back twice from a break down against Japan’s Yoshihito Nishioka to put Spain into the ATP Cup quarter-finals in Australia.
The world number one won 7-6 (7-4) 6-4) to give Spain an unassailable 2-0 lead in the tie after Robert Bautista Agut had earlier beaten Go Soeda 6-2 6-4.
Nadal then paired up with Pablo Carreno Busta to win the doubles rubber and end Japan’s chances of a last-eight spot.
Argentina later beat Croatia to advance to the knockout stage.
Canada and Belgium sealed the two remaining quarter-final spots as the best runners-up.
The knockout stage, taking place in Sydney, begins on Thursday with Great Britain facing hosts Australia (from 23:00 GMT on Wednesday).
The ATP Cup is a new 24-nation knockout tournament that has been set up by the men’s professional tour to kick off the 2020 season.