Serena claims 'discrimination' over drug tests

Serena Williams claims she is the victim of "discrimination" by US doping chiefs who are testing her more than other players.

At Wimbledon Williams slammed "shocking" treatment over excessive targeting from testers in the run-up to the second Grand Slam of the season.

And in a tweet on Wednesday the 23-time Grand Slam winner reignited the discussion.

".....and it's that time of the day to get "randomly" drug tested and only test Serena," she posted.

"Out of all the players it's been proven I'm the one getting tested the most. Discrimination? I think so. At least I'll be keeping the sport clean #StayPositive," she wrote.