The Spaniard is the clear favourite to win his 11th title in Monaco considering that he has lost just 16 games in four matches in the tournament.
A win will not only help Nadal retain the top world ranking ahead of Roger Federer but also set a new record (31) for winning the most number of Masters titles.
The first set against of the Nadal-Dimitrov was a tight affair. Though Nadal raced to a 3-0 lead in the first set, Dimitrov fought back to level the score 3-3. However, Nadal broke Dimitrov again to wrap up the set in 65 minutes.
Nadal breezed through the second set breaking Dimitrov twice to seal the win.
The 36th ranked Nishikori reached his fourth Masters final after defeating third seeded Zverev 3-6, 6-3, 6-4 and reach his first Masters final since Toronto in 2016.
Australia back into Fed Cup World Group
Australia returned to the World Group of the Fed Cup after beating the Netherlands 4-1. Daria Gavrilova beat Quirine Lemoine 6-3, 6-2 in the fourth singles to give Australia the winning lead.
Earlier, Australia’s Ashleigh Barty had defeated Lesley Kerkhove 6-4, 6-2 in the third singles rubber.
Gavrilova teamed with Destanee Aiava to win the fifth doubles rubber, 6-3, 6-2.