Serena Williams pulled out of next week's Nasdaq Open in Miami yesterday, citing a knee injury and lack of training.

Williams, who has not played since losing in the Australian Open third round in January, has been fined heavily by the WTA Tour for pulling out of several tournaments this year.

She underwent knee surgery in 2003 and has not won a title since taking her seventh grand slam crown at the 2005 Australian Open.

She has only played in nine tournaments since and is currently ranked 58th in the world, her lowest mark in seven years.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.