Roger Federer returned to Roland Garros unsure whether he can write yet another extraordinary chapter in his storied career.
The 37-year-old is making a first appearance at the French Open since 2015 having skipped the clay season for the last couple of years to try to give himself the best chance of success on the grass.
He compared the feeling to the 2017 Australian Open, when he was coming back from the first long injury break of his career.
The good news for Federer fans is that he won that tournament in probably the only surprise of his 20 grand slam titles, but a 21st success here would be a different scale of upset.
Asked if he believed he could win the title, the third seed said: "I don't know. It's a bit of a question mark for me. In some ways I feel similar to maybe the Australian Open in '17. A bit of the unknown.
"I feel like I'm playing good tennis, but is it enough? Or is it enough against the absolute top guys when it really comes to the crunch? I'm not sure if it's in my racket. But I hope I can get myself in that position deep down in the tournament against the top guys.
"But first I need to get there and I know that's a challenge in itself. It's definitely going to be an exciting tournament mentally to go through."
Federer has played two tournaments in the build-up, losing a very close battle to Dominic Thiem in the quarter-finals in Madrid and then pulling out ahead of a scheduled last-eight clash with Stefanos Tsitsipas in Rome having played two matches the previous day.
"I think I have been able to train hard enough and also got the necessary tough matches in Madrid and Rome, more than I would have liked to, but I guess we like saving match points or trying to lose with match points," said Federer, whose last title on clay came in Istanbul in 2015.
"But I really feel like playing under the pressure and playing with the nerves was important for me so I feel totally ready."
It is 10 years since Federer won his only French Open title, seven since he went beyond the quarter-finals and 20 since he made his debut as a 17-year-old wild card.
Federer is the only player in the men's draw this time who was also there in 1999, but there have been more changes to Roland Garros in the past 12 months than in the previous 19 years.
The centre court, Philippe Chatrier, has been 80 per cent rebuilt, with a roof to be added for next year's tournament, while a new third court has been built in the neighbouring botanic gardens surrounded by greenhouses.
"A lot of things have changed," said Federer. "Centre court looks very different. There has been a lot of upgrades and investments made. It's definitely growing and it's nice to see. I feel still it is the old Roland Garros, it's kept its flair and everything."
There was another withdrawal from the men's event on Friday as Nick Kyrgios pulled out through illness despite not being due to play his first-round match until Monday or Tuesday.
Having been defaulted from his last match in Rome last week after throwing a chair across the court, Kyrgios caused another stir ahead of the tournament by saying the French Open "sucks" compared to Wimbledon.
Kyrgios had been due to face Britain's Cameron Norrie, who will now take on French qualifier Elliot Benchetrit instead.