Serena Williams, playing her first match since regaining the world number one ranking, made a triumphant start to the Sony Open, thumping Italy’s Flavia Pennetta 6-1 6-1 in Florida, on Thursday.

Playing her first match after a bye, Williams made a sloppy start, hitting two double faults in her opening service game, but was unstoppable once she found her rhythm.

“I think I was off, footwork-wise, but it’s always good to win a match and then just keep going,” Williams said.

“There’s nothing like when they announce you and they say, ‘the number one player in the world’.

“It definitely gives me a little bit more confidence, I think a little bit more pep in your step. It’s just a great feeling.”

At 31, Williams is already the oldest woman to reach the top of the rankings.

China’s Li Na also made a flying start to the tournament, winning her first match since losing in the Australian Open final.

Li, beaten by Victoria Azarenka in Melbourne, reeled off the last 10 points of the match to beat Kiki Bertens, of Holland, 6-3 6-1.