Caster Semenya marked her return to Diamond League action with victory in the 800 metres at the Prefontaine Classic.

The South African athlete, who had missed the previous two races as a result of the IAAF's controversial female eligibility rules, led the field home at Stanford in 1.55.70, beating her own meeting record in the process.

She finished 0.66 seconds ahead of Ajee Wilson with Raevyn Rogers in third, both Americans recording season-best times.

Semenya was free to run after launching an appeal with the Swiss Federal Court against the IAAF's differences of sex development regulations following defeat in her challenge at the Court of Arbitration for Sport.

Under the rules, the double Olympic and three-time World 800 metres champion would be forced to take medication to suppress her high level of testosterone.