Roger Federer and Serena Williams hope to defy the doubters when they get their Wimbledon campaigns underway on 'Super Tuesday' at the All England Club where a backlog of matches needs to be cleared after the opening day downpours.
Serena, a seven-time Wimbledon champion, is still one shy of Margaret Court's Grand Slam singles record of 24.
Williams remains in the top 10 in the world but bowed out early in the French Open and the days of her holding a psychological edge over players appear to have gone.
Eight-time winner Federer, like Williams edging closer to his 40th birthday, had a disappointing second round exit at Halle -- his traditional warm-up for Wimbledon which he has won 10 times.
He starts against Frenchman Adrian Mannarino who has reached the fourth round at Wimbledon three times.
It falls to Mannarino to restore French pride and a measure of revenge too after Federer's Swiss compatriots dumped world champions France out of Euro 2020 on Monday.
Federer says his longevity was not something he planned.
"Truthfully, I don't think my goal was to play till, whatever, 39 or 40 or more," he said.
"It was maybe more like 35 I was thinking, which was already a high number at the time."
Federer lost an epic final to Novak Djokovic two years ago despite holding two championship points.
Last year he underwent two knee surgeries.
- 'Big X on my back' -
Williams faces Aliaksandra Sasnovich of Belarus.
The American has never lost a first round match at Wimbledon, posting a 19-0 record.
Indeed, she has only ever lost one opening round match in 78 major appearances.
Williams, though, acknowledges that with her legend status every player she faces ups their game.
"I've had a big X on my back since '99, since I won the US Open," she said.
"When players play me that hard every single tournament, every single match, every single Grand Slam, it just doesn't matter where, you just get better.
"Yeah, it's been difficult mentally when someone might beat you and they lose directly in the next round almost every time."
One of the big barriers to Williams's goal of equalling the controversial Court's record will be Ashleigh Barty.
The 25-year-old world number one has the honour -- in the absence of 2019 champion Simona Halep -- of opening on Centre Court against Carla Suarez Navarro.
The 32-year-old Spaniard is likely to have the crowd on her side after being diagnosed and then beating Hodgkin's lymphoma in April.
Unlike Williams, Suarez Navarro wants to compete at the Olympics in Tokyo in her final year in the sport.
However, before then she says she is going to enjoy her last appearance on the lawns in South West London where she has twice reached the fourth round.
On both occasions she found first Venus Williams (2016) and then Serena (2019) too good for her.
"Any chance to play here, at this beautiful place is incredible," she told Wimbledon.com.
"It's all green, all perfect and also all white."
Only 32 of the scheduled 64 singles matches were completed Monday due to rain and fading light.
Tuesday's bumper programme also includes second seeded Russian Daniil Medvedev, fresh from his first grass court title in Mallorca, facing Jan-Lennard Struff.
The German player defeated Medvedev in Halle earlier this month.
Coco Gauff, who made the last 16 in 2019 as a 15-year-old qualifier, is seeded 20 and faces British wildcard Francesca Jones.
Venus Williams, the five-time winner, faces Romania's Mihaela Buzarnescu while French Open champion Barbora Krejcikova tackles Clara Tauson of Denmark.
Also on the schedule is Australian crowd-pleaser Nick Kyrgios who plays France's Ugo Humbert.
The two of them played out a thrilling five setter at the Australian Open which Kyrgios won but Humbert showed his class on grass to win at Halle.