(CNN) -- Rafael Nadal crashed to an early upset defeat at Wimbledon for the second year in a row as the fifth seed was sent packing in straight sets Monday by Belgian Steve Darcis in their first round match.
Looking a shadow of the player who claimed a record eighth French Open title earlier this month, the Spaniard succumbed meekly 7-6 7-6 6-4 in a shade short of three hours on Court One.
Last year he was beaten in the second round by Czech Lukas Rosol, the prelude to a lengthy injury layoff which saw him miss the London Olympics and the next two grand slams.
Nadal only returned to the ATP circuit in February and has been in imperious form, winning seven titles, including the French Open.
With the exception of a hard court tournament in the United States, only one of the events has been on a surface other than his favored clay.
But coming into Wimbledon and despite his lack of preparation on grass, Nadal was rated among the favorites despite his lowly seeding.
However, he has fallen at the first hurdle, beaten by the 29-year-old Darcis, who was securing the most notable victory of his career.
Throughout the match, Nadal, who has a history of knee problems, appeared to be nursing an injury and looked slow and sluggish.
After claiming the first two sets on tiebreaks, the second time after coming back from a break down to Nadal, Darcis made an early breakthrough to lead 2-0 in the third set.
Nadal could make little impression on his service and Darcis duly served out for the match, clinching it with his 13th ace.
"Nobody was expecting my win today. I don't know what to say. I'm really happy," Darcis said after his unlikely triumph.
"OK, Nadal didn't play his best tennis, but I knew the first match on grass is always difficult. For me it is a big win.
"He lost early last year as well, but if you try to focus on him it is tougher. I try to focus on myself and I think I did great today."
Journeyman Darcis, who has been campaigning for most of 2013 on the second tier ATP Challenger Tour, had only previously reached the second round at Wimbledon in 2009.
"I always played good on grass, maybe not here because I had tough draws, but I have two wins against top 10 players on grass," he added.
Nadal refused to use any possible injury as an excuse for his defeat, the first time he had lost in the opening round of a grand slam.
"It's not the right day (to talk about his knees) I tried my best in every moment, but it was not possible this afternoon," said Nadal.
"On grass, it's difficult to adapt when you don't have a chance to play on the surface before Wimbledon. Darcis deserved to win today."
Earlier, Nadal's arch rival Roger Federer breezed through the opening match of his bid for a record eighth Wimbledon crown -- then spared a thought for the "influential and amazing" Nelson Mandela, who is in critical condition in a Pretoria hospital.
The defending champion dropped just five games in beating Victor Hanescu of Romania, finishing by taking the final set to love.
"There was just a bit of a breeze and it was cold. I'm happy to get out of there early and quickly. So it was a perfect day," was the Swiss maestro's initial verdict on a peerless performance in his opener.
When asked about former South African president Mandela, Federer said he hoped the 94-year-old would make a recovery.
"He's been very influential, an amazing personality, you know, believed in something, had to pay a big price for it," he added.
"Someone you can definitely look up to and that's very important for me. Clearly there's many that come and go, but he has been there for a very long time and he's very much respected and loved."
In a 2011 global study of more than 50,000 people in 25 countries, Federer had been ranked second only to Mandela as a respected, admired and trusted personality.
His mother Lynnette also hails from South Africa and he is a regular visitor to the country for charitable activities.
Home hope Andy Murray also had an easy passage into the second round, easing past Benjamin Becker of Germany in straight sets, 6-4 6-3 6-2.
In the final match of the day, Lleyton Hewitt of Australia rolled back the years to knock out 11th seed Stanislas Wawrinka of Switzerland.
The champion 11 years ago beat the dangerous Wawrinka 6-4 7-5 6-3, showing a return to his best form after being dogged by injuries in recent years.