The Spaniard levelled the Davis Cup quarter-final tie against Germany at 2-2 after two hours and 16 minutes, breaking the 20-year-old on six occasions en route to his second three-set win in three days.
Zverev had already comfortably beaten David Ferrer 6-4 6-2 6-2 but Germany earned a surprise victory in the doubles as Jan-Lennard Struff and Tim Puetz stunned Feliciano Lopez and Marc Lopez 6-3 6-4 3-6 6-7 (4-7) 7-5.
Lucas Pouille, the world No 11, gave France the first point in Genoa with a 6-3, 6-2, 4-6, 3-6, 6-1 win over 62nd-ranked Andreas Seppi.
"No, probably will be better to come back in the best of three sets, not best of five sets", Nadal was quoted as saying by the Express.
Nadal has since returned to full training and will make his debut when Spain take on Germany in the quarter-finals of the Davis Cup.
It was also the 24th consecutive match Nadal has won in Davis Cup. "I think Philipp played one of the best matches I have ever seen him play". "He is not at 100% yet, but if he can win a match or two, it can help him", Moya said.
"But I am excited to be back - hopefully it will be a positive week for me".
With the doubles coming up tomorrow, Nadal has a break before his scheduled - and potentially crucial - singles match against Zverev, which will be followed by a final singles match between Ferrer and Kohlschreiber.
Top-ranked Nadal cruised to a 6-1, 6-4, 6-4 win over fourth-ranked Alexander Zverev in the first match Sunday to keep Spain alive after entering the day trailing 2-1. "We got a bit lucky but it feels great".
Croatia are also one win away from the last four after Ivan Dodig and Nikola Mektic defeated the Kazakh pair of Timur Khabibulin and Aleksandr Nedovyesov 6-7 (2-7) 6-4 6-4 6-2.
Croatia made the semi-finals when Marin Cilic hammered Kazakhstan's Mikhail Kukushkin 6-1, 6-1, 6-1 to seal their tie 3-1.
April 7, 2018; Nashville, TN, USA; John Isner (USA) and Sam Querrey (USA) and Jack Sock (USA) and Ryan Harrison (USA) and Steve Johnson (USA) celebrate winning the Davis Cup tie against Belgium at Belmont University.