Caster Semenya has eased to victory in the women's 800 metres at the latest Diamond League event in California

Semenya is back racing the event again after a Swiss court ordered the International Association of Athletics Federations to suspend implementation of new regulations.

The IAAF is trying to ban athletes with abnormal testosterone levels from competing in women's distances from 400 metres to 1500 metres.

Meanwhile New Zealand's Tom Walsh will come up against the best field he's faced this year.

Walsh meets Olympic Champion Ryan Crouser, Darrell Hill and Tomas Stanek, who all have personal bests of over 22 metres.

The competition is about to get underway