Maria Sharapova made a convincing start to her U.S. Open title campaign on Monday and then turned comedian as she revealed her build-up had been affected by a "pregnancy" scare.

The Russian was forced to miss events in Montreal and Cincinnati earlier this month because of a stomach bug she first felt on the eve of the Olympic final, in which she lost to Serena Williams.

"I had some tests done, some blood-work, some ultrasound stuff," Sharapova told reporters after her 6-2 6-2 win over Melinda Czink of Hungary.

"They said I should just probably rest. I just went home and took Cincinnati off as well. I think it was just a sign that I needed a few weeks off.

"It was really weird. They told me I was fine, not pregnant. I'm like, can I get my money back?"

Sharapova was reluctant to use the bug as an excuse for the Olympic final, where she was hammered 6-0 6-1 by Williams.

"It was worse when I got to Montreal," the third seed said. "At the end of the day, I think it was some stomach bug. But I thought it was getting better. Then I started eating like the normal Maria and it wasn't better."

The rest seemed to have done her good though as the Russian coped well with a testing wind and humid conditions to see off Czink with the minimum of fuss.

"It was really weird. They told me I was fine, not pregnant. I'm like, can I get my money back?" - Maria Sharapova.

Sharapova broke twice to win the first set and reeled off the last three games to set up a clash with Lourdes Dominguez Lino of Spain in the second round.

"I was just happy to be back playing a competitive match," she said.

"Its been a few weeks. It was a nice break in a way but after so many weeks of practising, you're just eager to get back on the court.

"The tournament almost seems a little bit easier because the practice is a little bit shorter getting ready to play matches. It's so much better than having practice weeks, to be honest.

"But I was happy with the way I came out. I'd never played my opponent before, a lefty, conditions weren't exactly perfect.

"Overall I played steady, but there's room for improvement, that's for sure."

The 25-year-old is chasing her second grand slam title of the year, having won the French Open in June to complete a career set of all four grand slam titles.