"I need to find the pieces, how to be happy, how to win matches."
Wawrinka, a quarter-finalist at Roland Garros in 2013 and tipped as a possible title contender after winning the Monte Carlo Masters crown last month, was the second top 10 seed to lose on a rain-hit day.
Japanese ninth seed Kei Nishikori had earlier lost 7-6 (7-4), 6-1, 6-2 to Slovakia's Martin Klizan.
There were no such problems for Rafael Nadal, Novak Djokovic and Maria Sharapova who all shrugged off the Paris gloom.
Eight-time champion Nadal, bidding to become the first man to win five Roland Garros titles in a row, beat US wildcard and world No 279 Robby Ginepri 6-0, 6-3, 6-0.
It was Nadal's 60th win at the French Open against just one loss.
World No 1 Nadal kicked off his campaign on the secondary Suzanne Lenglen court while title rivals Djokovic and Wawrinka were handed top billing on the main Philippe Chatrier arena.
But it was still business as usual for Nadal who fired 27 winners past Ginepri, a semifinalist at the 2005 US Open whose challenge was undone by 41 unforced errors. "It doesn't matter where I play," said Nadal who next faces highly-rated Dominic Thiem of Austria.
"It's always a pleasure and an honour to play at Roland Garros, on Chatrier, Lenglen or any other court. This place has given me unforgettable emotions."
Second seed Djokovic, the 2012 runner-up who is seeking a first Roland Garros title to complete a career Grand Slam, brushed aside Portugal's Joao Sousa, the world 42, in straight sets, 6-1, 6-2, 6-4.
Sharapova, seeded seven and the 2012 champion, needed just over an hour to beat fellow Russian Ksenia Pervak, the world's 156th-ranked player, 6-1, 6-2.
Australian 18th seed Samantha Stosur eased past Puerto Rico's Monica Puig 6-1, 6-1 despite having had five stitches in a gashed leg.
-AAP