The 10-time champion enjoyed a satisfactory afternoon at the office as he improved his outstanding record in the principality to 64 wins from 68 matches.
Nadal, who must lift the title on Sunday to maintain his slim advantage over Roger Federer at the top of the rankings, was rarely troubled by his opponent.
The Slovenian, a complete performer with neat and tidy groundstrokes, lacked the firepower necessary to unsettle his illustrious rival on a clay-court. The 28-year-old competed well though, and the one-sided nature of the scoreline doesn’t accurately reflect his effort.
Nadal was in cruise control from the moment he moved 2-0 ahead with a trademark forehand passing-shot winner whipped cross-court. It was the perfect start for the world No.1, and he dropped just a single game as he pocketed the opening gambit.
Bedene managed to stay with the ‘King of Clay’ until the seventh game of the second set before eventually being outmuscled. Nadal stepped on the accelerator and completed a routine victory in just 78 minutes.
“Playing on a court where I’ve had a lot of success in the past always provides a little extra confidence, but at the same time, every year is a different story,” said Nadal.
“This year is a little bit special for me. I have been away from competition for almost five months. I played the Australian Open, but nothing else. Since Shanghai (last October) I did not complete one event, so it was important for me to start with a victory.
“I need matches and I need to find my rhythm again.”
Earlier in the day, Novak Djokovic held off a spirited fightback from Borna Coric to set up a mouth-watering last sixteen clash with Dominic Thiem.
The former world No.1 took out the tenacious Croatian 7-6(2) 7-5 to net just his fifth victory of a difficult season. It was, as expected, a baseline battle between two outstanding defenders, however the Serbian’s greater quality shone through when it mattered most.
It took Djokovic 10 match points to eventually see off his plucky rival, but he was not to be denied the chance to continue his bid for a third title in Monaco.
Also on day four, Kei Nishikori overcame Daniil Medvedev 7-5 6-2, Richard Gasquet took out Diego Schwartzman 6-2 6-1, Roberto Bautista Agut manoeuvred past Feliciano Lopez 6-3 7-6(5) and Jan-Lennard Struff upset Fabio Fognini 6-4 6-2.
Philipp Kohlschreiber, who suffered a painful loss to David Ferrer in the Davis Cup last week, knocked out last year’s finalist, Albert Ramos-Vinolas, 6-4 6-2.
Milos Raonic and Karen Khachanov are also through to the last sixteen.