Caster Semenya laid down a marker in the race for 400 metres gold at the Rio de Janeiro Olympics in August by running the fastest time of the year at the South African Championship on Saturday.
She clocked 50.76 seconds, eclipsing the previous 2016 best of 50.91 by American runner Jaide Stepter registered in Los Angeles last month.
Semenya also claimed the South African 800 metres title in Stellenbosch, near Cape Town, in 1.56:48.
She is also the fastest competitor in that event this year as well.
She won the silver medal in the 800 at the 2012 London Olympics and hopes to add the 400 to her list of events in Rio.
Semenya has already run under the qualifying time in both distances.
The 25-year-old is back this season after almost two years away from the track with a knee injury.
Semenya was subjected to gender tests by the International Association of Athletics Federations (IAAF) in 2009 before being cleared to compete as a woman 10 months later.
