Maria Sharapova was feeling off colour - but her game looked in good health as the French Open champion opened her title defence with a 6-2, 6-4 first-round win against Estonia's Kaia Kanepi.

The second seed, who will next face fellow-Russian Vitalia Diatchenko, was barely bothered by a cold in a late-afternoon canter on Philippe Chatrier court.

"I'm getting over it, and hopefully it will pass by soon," said Sharapova, who warmed up for Roland Garros by winning the Italian Open.

She added: "I had a tough opponent ahead of me. I knew that it was going to be tough and it wasn't going to depend on the tennis.

"And the conditions were pretty difficult as well. So really, overall just happy I got through and have a day off today and I should be better by then."

Sharapova wasted no time in post-match interviews to the disappointment of the crowd who booed her off court.

"Of course I totally understand that, you know, everyone usually does post-match interviews and answers a few questions to the crowd. It's absolutely normal," she said.

"I'm not making any excuses, but I've got to do what I have to do."

Meanwhile, Britain's Heather Watson overcame her nerves to see off the challenge of home hope Mathilde Johansson 6-4, 7-5, and claim a place in the second round against either 15th seed Venus Williams or Sloane Stephens.