Serena Williams

US star Serena Williams has pulled out of the Monterrey WTA tournament next week citing a niggling ankle injury, event organisers said yesterday.

The former world number one had received an invitation for the tournament which starts on Monday.

But organisers said they had received a statement from the WTA saying that the 30-year-old would not be able to accept the invitation.

The world number 12 will however play an exhibition match against Argentine Gisela Dulko on Sunday.