After eight days of drama, the first-ever ATP Cup has come down to Serbia vs. Spain. (Getty Images)

After eight days of drama, the first-ever ATP Cup has come down to Serbia vs. Spain.

On Friday, world No. 1 Rafael Nadal suffered an unexpected singles loss in the semifinals to David Goffin. But on Saturday, he pulled off a critical comeback win over Alex de Minaur, 4-6, 7-5, 6-1 to clinch the final berth over Australia. 

His teammate Roberto Bautista Agut has been flawless this whole tournament, having not lost a match. Agut's 5-0 record in 2020 includes a 6-1, 6-4 win over Nick Kyrgios in Spain's win to kick off the semifinal. 

But, world No. 2 Novak Djokovic has also been undefeated. He has topped Kevin Anderson, Gael Monfils, Cristian Garin, Denis Shapovalov and Daniil Medvedev. His win over Medvedev put Serbia into the final. 

Serbia's No. 2 Dusan Lajovic has done more than his fair share of the heavy lifting, with a 4-1 record including an upset of Karen Khachanov. 

The match between Nadal and Djokovic on Sunday will be their 55th career meeting.