Nadal, 38, made his earliest exit at the clay-court major he won 14 times following a first-round defeat by Alexander Zverev last year, but did not say then if it was the last time his adoring Parisian fans would watch him in action.
The 22-time Grand Slam champion called time on his career after playing for Spain in the Davis Cup in November and is back in his favourite hunting ground, where a special tribute is planned after the day session.
While the ceremony is expected to bring together Nadal and fellow greats of the sport, fans were focused on the new generation of players, including defending champion Carlos Alcaraz.
"Nadal is not playing anymore and if last year we felt that Novak Djokovic could be strong, we don't feel that this year," said Thomas Dehedin, a building project manager.
"It's really the new generation coming, it's nice. There is a bit of suspense. We'll see if Alcaraz can take Nadal's mantle. He made a great start to the season on clay."
The Panama hats and sunglasses were stowed away for and replaced by jackets and umbrellas with short spells of rain around Roland Garros, where Lorenzo Musetti, Ben Shelton and Jasmine Paolini are all in action on day one.