Semenya eases through 800m heats, Arzamasova out

Athletics - World Athletics Championships - Women's 800 Metres Heats - London Stadium, London, Britain – August 10, 2017. Caster Semenya of South Africa reacts after winning the heat. REUTERS/Phil Noble

LONDON (Reuters) - Olympic champion Caster Semenya maintained her two-year unbeaten record over 800 metres as she eased through the first round at the World Championships on Thursday.

Her main challengers, Francine Niyonsaba, Margaret Wambui and Ajee Wilson, also cruised into Friday's semi-finals but defending champion Maryna Arzamasova was eliminated after finishing fourth in her heat.

Athletics - World Athletics Championships – women’s 800 metres – London Stadium, London, Britain – August 10, 2017 – Angela Petty of New Zeland, Caster Semenya of South Africa and Rose Mary Almanza of Cuba compete. REUTERS/Phil Noble

South African Semenya, last beaten at the World Championships semi-final in Beijing two years ago, was third going into the final straight and eased past Rose Mary Almanza and Natoya Goule to win in 2:01.33.

"I just want to keep winning. That's all I'm concentrating on. I'm feeling okay after the 1,500 metres, so I'm ready to go again," said Semenya, who won bronze in the 1,500 on Monday.

Wilson, who became the first American to run under 1.56 seconds when she set a national record in Monaco last month, comfortably won the first heat in 2:00.52.

Athletics - World Athletics Championships – Women's 800 metres heats – London Stadium, London, Britain – August 10, 2017 – Caster Semenya of South Africa reacts REUTERS/Lucy Nicholson

"I'm definitely in the best shape of my life as my time in Monaco before the championships showed," Wilson said. "I've never run so well and so consistently during my career."

Burundi's Niyonsaba and Kenyan Wambui, silver and bronze medallists respectively in last year's Olympics, also won their heats.

Arzamasova led the fourth heat on the last lap but faltered badly at the finish to be pipped for the third automatic place by Halima Nakaayi. She was not among the six fastest losers.

Athletics - World Athletics Championships – women’s 800 metres – London Stadium, London, Britain – August 10, 2017 – Joanna Jozwik of Poland and Caster Semenya of South Africa react. REUTERS/John Sibley

Kenyan Eunice Sum, the 2013 world champion, withdrew due to illness.

(Editing by Ed Osmond)

Athletics - World Athletics Championships - Women's 800 Metres Heats - London Stadium, London, Britain – August 10, 2017. Caster Semenya of South Africa and Natoya Goule of Jamaica after the heat. REUTERS/Phil Noble

Athletics - World Athletics Championships – Women's 800 metres heats – London Stadium, London, Britain – August 10, 2017 – Caster Semenya of South Africa competes REUTERS/Lucy Nicholson

Athletics - World Athletics Championships – Women's 800 metres heats – London Stadium, London, Britain – August 10, 2017 – Caster Semenya of South Africa competes REUTERS/Lucy Nicholson