Caster Semenya provided the perfect response to being told she has to take drugs or change events if she wants to continue competing by storming to victory in the 800 metres in the opening Diamond League meeting of the season in Doha.

Two days after the legal judgement which will force her to take medication to reduce her testosterone levels if she wants to be eligible to defend her world title later this year, the two-time Olympic champion did what she does best.

The South African powered clear of the field to claim a comprehensive victory in what could prove the last international 800m race of her career.

Semenya, who raised a clenched fist in the air when she was introduced to the crowd, sat on the shoulder of the pacemaker early on before bursting away to cross the line in one minute 54.98 seconds, the fastest time in the world this year and a meeting record.

There appeared to be little emotion at the finish, just a thumbs-up for the cameras.

The 28-year-old is the dominant force in women's 800m running – a five-time global champion, the fourth fastest in history over the distance and the world number one in each of the last three seasons.

However, the Court of Arbitration for Sport's decision to rule the controversial testosterone limit for female runners introduced by athletics world governing body the IAAF "necessary", even if it is "discriminatory", is set to have major ramifications on the rest of her career.

The stark choice facing Semenya now is: start taking hormone suppressants – the IAAF says she and other athletes with differences of sex development have until May 8 to reduce their testosterone levels to five nanomoles/Litre of blood serum – change events, with all from the 400m to the mile affected by the IAAF's new regulations, or retire.

And it is not just a choice facing her.

Burundian Francine Niyonsaba, who finished second to Semenya in 1min 57.75secs, as she did at the 2016 Olympics and 2017 World Championships, will also be affected by the rules.

But whatever the future holds, Semenya's run on Friday night was certainly a statement to her detractors – a time faster than she ran to win any of her two Olympic or three world titles.

Semenya, who was a late addition to the field in Doha and received a warm reception from the crowd, had hinted at retirement on social media in the wake of the CAS judgement, but emphatically ruled that out after the race.

"How the hell am I going to retire when I'm 28? I still feel young, energetic," she was quoted as saying by BBC Sport.

"I still have 10 years or more in athletics – it doesn't matter how I'm going to do it, what matters is I'll still be here."

She added: "I'm never going anywhere. At the end of the day, it's all about believing.

"It's up to God. God has decided my career and he will end my career, so no human can stop me from running."

Great Britain's Dina Asher-Smith also claimed an emphatic victory in Doha, clocking 22.26 to win the 200m.

"I ran faster than I thought I would so I'm really happy," she said.