Ohuruogu turns on the power as British quartet impress on the track

Christine Ohuruogu eases into the 400m final

Sanders was handed a tough draw in lane nine and could only finish fourth in the last semi-final in 50.71secs to miss out, as did team-mate Lee McConnell who was sixth in the second semi.

Pre-championship favourite Sanya Richards - absent from Osaka last year - was the fastest qualifier in 49.90s.

Britain's women also enjoyed success on the track through Jeanette Kwakye in the 100m, Tasha Danvers in the 400m hurdles and Sarah Claxton in the 100m hurdles.

Kwakye turned a brilliant start into a place in the Olympic final, blasting out of the blocks with a reaction time of just 0.156s and holding on down the closing stretch to finish third in her semi-final in a time of 11.19s.

The 25-year-old from Essex was not certain she had made it but jumped with
delight after seeing it confirmed on the giant scoreboard and will be back on
the start line at 2225 local time (1525 BST) for the final.

A delighted Kwakye, whose time was just 0.01s outside her personal best, said:
'That was amazing. There was no other option for me today but to get into that
final and I've done it.

'I knew I had it in me to get to the final and it has been my little secret
target for the season and I'm absolutely chuffed that I did it.'

A revised start list had to be issued for the 400m hurdles after 2004 champion
Fani Halkia failed a drugs test while preparing for the Games in Japan.

Danvers was in the second of four heats and had no problems advancing to the
semi-finals, winning her heat in a time of 55.19s, comfortably an injury-plagued
season's best.

The 30-year-old Los Angeles-based Londoner said: 'I'm so happy because it has
been horrendous this season, there's no other way to put it.

'I was thankful just to be in the team but it's scary when you have a season
like I have because there's no way knowing what you are going to do. I could
have done anything from 59 to 54 seconds. It's like I've been in no-man's land.

'It has been rough, an Achilles, three hamstring tears and a virus but I'm
still standing. To be honest with you when I got to the straight and I was in
front comfortably it was like 'What's going on?' but then I said to myself
'Yeah, you are a champion, let's go'.

'I tried to ease in to keep something left in my legs for tomorrow, and I feel
really good - this has just done wonders for my confidence.'

Claxton advanced to the semi-finals of the sprint hurdles after finishing third
in her heat in a time of 12.97 seconds, enough to advance as one of the six
fastest losers.

'I'm quite pleased with that, I've improved a lot on my time in Athens,' said
the 28-year-old Londoner. 'I've definitely got more to come because that race
was quite messy and I hit two of the hurdles so I know I can do better in the
semi-final.'

Ireland's Derval O'Rourke failed to advance after causing a false start and
then only finishing sixth in her heat in 13.22s.