Nadal has not played since the middle of last month when he was forced to withdraw from his Indian Wells semi-final with Roger Federer due to a knee injury.
But the Spaniard had no doubts he would be ready for the start of the clay court season and that confidence appears to have been justified.
The 11-time French Open champion has been practising at his academy in Mallorca over the past 10 days.
And he arrived in Monaco earlier today and by the afternoon he was at the Monte Carlo Country Club getting back to work on Court Rainier III in a light session with Serbian Dusan Lajovic.
Nadal will be part of the draw ceremony, which begins at 5.30PM GMT.
As one of the top eight seeds, Nadal will begin his campaign for an astonishing 12th title in Monte Carlo on Tuesday or Wednesday.
How many ATP ranking points does Rafael Nadal have to defend?
MONTE CARLO – 1000 points
BARCELONA – 500
MADRID – 180
ROME – 1000
FRENCH OPEN – 2000
Who are the top eight seeds?
1. Novak Djokovic (SRB)
2. Rafael Nadal (ESP)
3. Alexander Zverev (GER)
4. Dominic Thiem (AUT)
5. Kei Nishikori (JAP)
6. Stefanos Tsitsipas (GRE)
7. Marin Cilic (CRO)
8. Karen Khachanov (RUS)