Former French Open champion Stan Wawrinka continued to struggle with form and fitness as he was dumped out in the first round by Guillermo Garcia-Lopez yesterday, a defeat which will send his world ranking plummeting, but Novak Djokovic cruised through in straight sets.

Wawrinka, who lost to Rafael Nadal in last year's final and won the 2015 title, was beaten 6-2 3-64-67-66-3 in a five-set thriller by the Spanish world number 67 on Court Suzanne Lenglen.

The 33-year-old has been plagued by a knee injury and arrived at Roland Garros having won just one match on clay in Geneva last week, his first event in three months.

The defeat means that the three-time grand slam champion will slip from 30th in the world to outside the top 250 after the tournament, having failed to defend the ranking points he gained in 2017.

"There is no frustration [at the rankings slip]. It's just tough," said Wawrinka.

"But again, I knew from the beginning that it will take long, a lot of time, to get back.

"I knew that from the surgery that it will take a year at least to get where I want to be."

Serbian star Djokovic had little trouble in reaching round two, though, seeing off Brazilian world number 134 Rogerio Dutra Silva 6-36-46-4.

The 12-time grand slam champion dropped serve three times and will have to improve markedly to challenge Nadal in the latter stages of the tournament, but he was still far too good for Dutra Silva on Court Philippe Chatrier.

"It was good to start this year with a win. I wasn't at my best; he played with a lot of spin. I didn't play very well, but I won in three sets," said the 20th seed, who will next face David Ferrer or Jaume Munar.

Former world number one Victoria Azarenka's return to grand slam tennis lasted just two sets as the Belarusian slumped to a 7-57-5 loss to Katerina Siniakova.

Petra Kvitova also found life hard, but the two-time Wimbledon champion fought back from a set down to beat Paraguay's Veronica Cepede Royg 3-66-17-5.

Kvitova, 28, is one of the favourites to win a maiden Roland Garros title after winning four titles this season, including on clay in Prague and Madrid. - AFP