The world No 1 proved he has fully recovered from a hip problem which had previously kept him sidelined since January.
Nadal cruised through the tournament, not dropping a single set in clashes against Aljaz Bedene, Karen Khachanov, Dominic Thiem, Grigor Dimitrov and Kei Nishikori.
But despite his stunning performance in the run up to Sunday's clash, Moya admits Nadal still felt he needed more practice before the final round.
"He played very well, feels well, is healthy, for him this part of the year is really important," he told Canal Plus.
"Winning Monte Carlo is very important.