Christine Ohuruogu cruises into 400 metres final at World Championships

Defending champion Christine Ohuruogu clocked her season's best time as she surged to victory in the 400 metres semi-finals at the World Championships.

The 31-year-old powered ahead of her rivals with a time of 50.16 seconds at the Bird's Nest stadium, taking 0.66secs off her previous best this year.

But Ohuruogu, who returned to the scene of her Olympic triumph seven years ago in Beijing, should face a sterner test in the final when she will line-up against American favourite Allyson Felix, who qualified fastest in 49.89s.

Felix was the only competitor to beat the 50-second mark, with Jamaica's Shericka Jackson crossing the line in second at 50.03 seconds. 

Shaunae Miller of the Bahamas won the first semi-final heat in 50.12, ahead of Christine Day of Jamaica in 50.82.

Great Britain's Anyika Onuora bowed out despite recording a personal best 50.87 in her semi while finishing fifth.

Ohuruogu said: "I got the job done. The job was to win the semi, that's all I can ask for and that competition should bring me what I need."

Usain Bolt and Justin Gatlin both cantered to victory in the opening 200 metres heats as the sprint rivals began their pursuit of more medals.

Bolt, who is targeting a fourth successive 200m world crown, flew out of the blocks and was able to ease up all the way down the straight, while Gatlin cruised across the line in his heat.

Brit duo of Danny Talbot and Zharnel Hughes are also safely through, with the latter winning his heat in 20.13 seconds despite running from a difficult lane.

"I want to get a medal here, but my focus right now is to get into the final," Anguilla-born Hughes said. "There's a lot of big rivals out there, but I am a big rival myself.

"I might be looking at people, but people are looking at me at the same time. I just have to go out there and run each guy like it's the final.

"Surprises are here. A lot of people have running fast on this track, so you never know what can happen."

Olympic champion and world record holder David Rudisha regained the 800 metres title after bursting down the back straight to win in one minute 45.84 seconds.  

Pole Adam Kszczot finished strongly to win silver in 1.46.08 and Bosnia and Herzegovina's Amel Tuka slashed more than three seconds off his personal best this year to finish third.

In the 1,500 metres, Ethiopian Genzebe Dibaba completed a dominant victory in a time of four minutes 08.09 seconds.

Dibaba outpaced the field over the final 800 metres, finishing ahead of Kenya's Faith Kipyegon, who won silver in 4.08.96, with Sifan Hassan taking bronze for the Netherlands in 4.09.34.

Kenyan policeman Nicholas Bett charged down the home straight to win the world championship 400 metres hurdles final on Tuesday.

Drawn in the outside lane nine, Bett had to run the race blind, unable to see his rivals until the final stages.