Nadal, who has won five titles since making his return after seven months out with a knee injury, won his 32nd match of the season against just two defeats.
He can move back to fourth in the rankings should he win another Rome title.
Nadal will next play Ernests Gulbis, a 6-1, 6-1 winner over Serb Viktor Troicki.
Results from the fourth day of the ATP and WTA Rome Masters/Rome Open (x denoted seeding):
Men:
Second Round:
Alexander Dolgopolov (UKR) bt Stanislas Wawrinka (SUI x15) - walkover
David Ferrer (ESP x4) bt Fernando Verdasco (ESP) 5-7, 7-5, 6-3
Philipp Kohlschreiber (GER) bt Albert Ramos (ESP) 6-4, 6-1
Ernests Gulbis (LAT) bt Viktor Troicki (SRB) 6-1, 6-1
Rafael Nadal (ESP x5) bt Fabio Fognini (ITA) 6-1, 6-3
Benoit Paire (FRA) bt Julien Benneteau (FRA) 6-7 (3/7), 6-4, 7-6 (7/4)
Jeremy Chardy (FRA) bt Kei Nishikori (JPN x16) 6-4, 6-1
Marcel Granollers (ESP) bt Andy Murray (GBR x3) 6-3, 6-7 (5/7) - retired
Jerzy Janowicz (POL) bt Jo-Wilfried Tsonga (FRA x8) 6-4, 7-6 (7/5)
Gilles Simon (FRA) bt Mikhail Youzhny (RUS) 7-5, 6-3
Women:
Second Round:
Dominika Cibulkova (SVK x14) bt Melanie Oudin (USA) 5-7, 6-1, 6-3
Carla Suarez (ESP) bt Romina Oprandi (SUI) 6-4, 6-2
Lourdes Dominguez (ESP) bt Yanina Wickmayer (BEL) 6-4, 6-4
Roberta Vinci (ITA x13) bt Nastassja Burnett (ITA) 6-1, 6-4
Jelena Jankovic (SRB) bt Bojana Jovanovski (SRB) 6-2, 6-0
Li Na (CHN x5) bt Zheng Jie (CHN) 6-3, 6-1
Samantha Stosur (AUS x9) bt Peng Shuai (CHN) 7-6 (7/5), 6-0
Ayumi Morita (JPN) bt Urszula Radwanska (POL) 6-3, 6-1
Sara Errani (ITA x7) bt Christina McHale (USA) 7-5, 5-7, 6-2
Maria Kirilenko (RUS x12) bt Varvara Lepchenko (USA) 6-3, 6-1
Sloane Stephens (USA x16) bt Kiki Bertens (NED) 4-6, 6-3, 6-2
Maria Sharapova (RUS x2) bt Garbine Muguruza (ESP) 6-2, 6-2