Serena Williams has vowed to work harder as she hopes to bounce back from yet another early defeat at a grand slam this season.

The American world No1 suffered a second consecutive defeat to French No25 seed Alize Cornet to make her earliest Wimbledon exit in nine years.

The loss comes close on the heels of a second round upset at the French Open last month and Williams admits she needs to make some changes.

“I worked really, really hard coming into this event. I’m going to have to keep working hard,” said the 32-year-old.

“Just because you lose a match doesn’t mean you stop. So I’ll just keep fighting, that’s all I can do really.

“The changes I need to make I think are mostly within. Just try to see why I am making some errors.“

Williams explained she draws motivation from the belief that she still has the game to remain at the summit of the rankings and that claiming an 18th grand slam to tie the tally of legends Martina Navratilova and Chris Evert (second most on all-time list) remains a target.

“I know that I can do better. I know that I have potential to continue to be on top. So hopefully that’s what keeps me motivated,” said Williams.

“I think (winning an 18th major) is definitely pretty significant. It’s something I’m obviously going to keep going for and it’s definitely something in my mind.”

Williams will join her sister Venus in doubles today but the world No1 admits she’s not really up for it.

“I suck right now at doubles. I told Venus the other day, I don’t even want to play because I’m so bad right now. She should get a new partner,” said Serena.