Argentina advanced to the quarter-finals of the Davis Cup on Monday , beating Brazil 3-2 after Federico Delbonis defeated Thomaz Bellucci 6-3 , 3-6 , 6-2 , 7-5 in a match that took two days to complete . The match had been suspended because of darkness on Sunday with Delbonis leading 1-0 . It started late after Leonardo Mayer needed six hours , 42 minutes to beat Joao Souza in the longest singles match ever played in the Davis Cup . Argentina 's Leonardo Mayer celebrates his country 's win by spraying sparkling win in Buenos Aires . Federico Delbonis beat Thomaz Bellucci to secure victory over Brazil and send Argentina to the quarter-finals . The 83rd-ranked Delbonis dropped the second set after play resumed on Monday but quickly rebounded to regain control . Argentina , who will next play Serbia , is returning to the World Group quarter-finals for the first time since 2013 . Juan Martin del Potro embraces his team-mate Delbonis - and Argentina face Serbia in the next round . Delbonis hits a shot during his 6-3 , 3-6 , 6-2 , 7-5 win over Bellucci at the Villa Martelli in Buenos Aires .
Thomaz Bellucci defeats Federico Delbonis to secure 3-2 win over Brazil . Leonardo Mayer took six hours , 42 minutes to beat Joao Souza . Their match was the longest singles match ever played in the Davis Cup . Argentina will play against Serbia in the next round .