(CNN) -- Australian Open champion Stanislas Wawrinka slumped to a tame defeat in the fading gloom of a rain-hit opening Monday at Roland Garros to Spanish outsider Guillermo Garcia-Lopez.
Third seed Wawrinka, who won the Monte Carlo Masters at the start of the clay court season, showed little of that form as he surrendered 4-6 7-5 6-2 6-0 on Philippe Chatrier to the world number 41.
The Swiss number one looked to restoring equilibrium when he took a hard-fought second set, but was outplayed in the remaining two to suffer an embarrassing first round exit in the second grand slam of the season.
He saved one match point a 0-5 down in the fourth but then completed a match of 61 unforced errors by hitting a backhand long.
Garcia-Lopez raised his arms in triumph while Wawrinka trudged off after the final action on the show courts after a weather-hit second day.
"It wasn't good at all, I kept trying to find my game, anything to get back in it but I just need to take a few days off now and figure out what happened," Wawrinka told gathered reporters after his defeat.
"He's a really good player but it was me, I couldn't find solutions and it was just terrible and a really big disappointment."
Earlier the two favorites for the men's title, eight-time champion Rafael Nadal and world number two Novak Djokovic eased their way through between the rain showers.
Nadal dropped only three games in a ruthless demolition of Amerian Robby Ginepri, while Djokovic could afford to delight the Philippe Chatrier crowd with an impromptu chat with a ball boy.
The 27-year-old Serbian was sitting under an umbrella during a break in play when he gestured to the young man to join him.
They sat for several minutes talking and Djkovic even offered his new friend a drink before clinking bottles with him.
The crowd lapped it up and burst into applause and after his 6-1 6-2 6-4 demolition of Portugal's Joao Sousa, Djokovic revealed the subject of the conversation.
"We had a nice chat," he told the official French Open website.
"He's a tennis player, so I asked him how long he's playing, and, you know, how he's enjoying his time as a ball kid.
"It was a nice, fun time, something unusual for the grand slams. He accepted the offer to sit down, which I didn't think he would do, but he did. So he's very spontaneous little boy, and I hope I see him my next match."
That will be against Frenchman Jeremy Chardy, with second seed Djokovic predicting a tougher test.
Defending champion Nadal was even less troubled by Ginepri, who has not won a match on the ATP Tour all season and but for a spell in the second set did not muster much resistance.
It was the top seed's 60th win at the French Open and he later shrugged off suggestions he had been snubbed by not playing on the main showpiece court of Philippe Chatrier and instead placed on Suzanne Lenglen.
A fellow professional had called the decision "bizarre" but Nadal claimed not to be bothered by the scheduling.
"It doesn't really matter a lot," he said.
"Roland Garros is a pleasure for me, is a really honor, and is a special feeling. So all the memories at this place give me are unforgettable.
"And doesn't matter if it's Chatrier or Lenglen or another court," added the Spaniard.
Nadal has suffered shock defeats in the clay court season and came close to losing in the final of the Madrid Masters to Kei Nishikori until the Japanese player succumbed to a back problem.
Great things were still expected of Nishikori at the clay court grand slam, but the ninth seed did not appear to have shrugged off his injury as he went out 7-6 6-1 6-2 to Slovak Martin Klizan in his opening match.
"It's tough for me, but I guess this is my tennis life, you know. I have to take care of my body and injury will come again, for sure. So I have to mentally be ready," he said.
"I have to do whatever I can do to get healthy."
In the women's draw there was an easy first round win for seventh Maria Sharapova as she beat fellow Russian Ksenia Pervak 6-1 6-2.
Sharapova, who lost last year's final to Serena Williams, needed only 27 minutes to wrap up the opening set and carried on her domination into the second.
She will now face Bulgaria's 2010 Wimbledon semi-finalist Tsvetana Pironkova for a place in the third round but Williams looms as a possible quarterfinal opponent for the 2012 champion.