Nadal bidding to avoid early French Open exit, Sinner shines
Second seed Sinner swatted aside Wimbledon quarter-finalist Christopher Eubanks 6-3, 6-3, 6-4 under the new roof on Court Suzanne Lenglen.
This year's event was expected to be 14-time champion Nadal's farewell to Roland Garros, but he has since insisted he could not confirm "100 percent" it would be his last appearance.
Nadal has only played four tournaments since January 2023 after suffering a hip injury and then a muscle tear.
That left him unseeded for the draw and vulnerable to a difficult opening round at a tournament where he has only lost three of his 115 matches.
World number four Zverev arrives in Paris as one of the favourites for the title after winning the Rome Open earlier this month.
"Of course on paper it is not the best draw," Nadal said ahead of the match on Court Philippe Chatrier.
"I play against one of the toughest opponents possible, and at the same time, he came here winning the last event and it's a Masters 1000.
"It's not a small one. So what can I do? That's the draw. Just try to be ready for it."
Nadal, who turns 38 in a week's time, has shown flashes of his best form in the clay-court swing, but was thrashed 6-1, 6-3 by Poland's Hubert Hurkacz in the second round of his last outing in Rome.
He boasts a 7-3 winning record over Zverev ahead of their first meeting since the 2022 French Open semi-finals, when the German left the court in a wheelchair near the end of the second set after injuring his ankle.
"I am not anxious. No, I am focused on trying to play well. That's it," said Nadal.
"Maybe I go there and I repeat the disaster of Rome. It's a possibility, of course. I don't want to hide that.
"But in my mind, is do something different and play much better and give myself a chance to play competitive."
'Didn't want' to play Nadal
Zverev did not play again in 2022 after that ankle injury but has climbed the rankings again in recent months.
The 27-year-old has long been touted as a future Grand Slam champion but remains without one of tennis' four biggest titles.
Clay is his strongest surface, though, and he has reached the semi-finals in each of the last three years at Roland Garros.
The men's draw looks far more open than usual, with doubts surrounding Nadal's fitness and Novak Djokovic having endured a turbulent start to the year.
"I can guarantee you Novak didn't want to play Rafa in the first round and (Carlos) Alcaraz didn't want to play, Jannik (Sinner) didn't want to play him," admitted Zverev.
"I don't want to play him in the first round, but it is how it is."
Sinner makes strong start
Australian Open champion Sinner started his title bid in confident fashion despite missing the Rome Open with a hip injury.
The Italian star struck 32 winners and broke Eubanks' serve five times as he set up a second-round meeting with French veteran Richard Gasquet.
"The hip is good, I'm very happy," said Sinner. "The general shape isn't at 100 percent yet so we're trying to build every day."
Marketa Vondrousova, a former Roland Garros runner-up and reigning Wimbledon champion, eased past Rebeka Masarova of Spain in straight sets before rain fell in Paris.
Tunisian eighth seed Ons Jabeur also booked her place in round two with a 6-3, 6-2 win over US wildcard Sachia Vickery on Chatrier.
Later on Monday, women's world number one Iga Swiatek starts her bid for a fourth French Open crown against home player Leolia Jeanjean.
Victory for the top seed will give her a second round clash with fellow four-time Grand Slam title winner Naomi Osaka.