The Spaniard was also securing the 46th clay-court title of his career, moving him level with the Open-era record for the surface which is held by Argentine great Guillermo Vilas, who was watching from the stands in Buenos Aires. ??
And Nadal now has 65 career titles on all surfaces, putting him in sole possession of fifth place on the Open Era all-time list led by the 109 successes of American Jimmy Connors.
The 28-year-old left-hander has battled injury since winning for the ninth time at Roland Garros and was beaten in the quarter-finals of the Australian Open before losing to Fabio Fognini in the semi-finals in Rio last week, dropping him down to fourth in the world rankings.
However, he proved too strong for Monaco as he defeated the local hope for the sixth time in six meetings after one hour and 26 minutes on court.
The pair had to wait out a two-hour rain delay before the match and another delay after both held serve for 1-1 in the opening set on the still slippery court.
After securing a tight first set with one break of serve, Nadal stormed through the second, breaking world No 60 Monaco twice en route to a 4-0 lead, then breaking him again in the final game.
“I had the hope of winning here and I prepared very well for this so it’s objective achieved,” said Nadal.