Briton Christine Ohuruogu's sharp dip at the line paid full dividends as she claimed the women's 400m crown at the World Athletics Championships on Monday.

The Briton, who won the 2007 worlds and took silver at the London Olympics after gold in Beijing, clocked a national record of 49.41sec in the one-lap race.

But Botswana's defending world champion Amantle Montsho had looked in prime position to finish atop the podium - until the final five metres.

Easing up slightly, Montsho's body had already moved into a more upright position as she slowed. Not so the experienced Briton, who came up with a savage dip to claim victory in a photo-finish.

Russian Antonina Krivoshapka claimed bronze in 49.78sec.

"It's like a dream, it's too much" said Ohuruogu. "I cannot believe it. After the race, I did not want to get too excited until I knew for sure that I won, until my name got out first.

"It's really weird. I'm just very happy."

Montsho said she was "happy and sad at the same time".

"At home they were expecting me to win gold here, so it is disappointing," she said. "But I'm still a medallist.

"I did not see Christine coming from behind. I know that I would have made it had I stuck my chest forward.

"But she knows how to run and how to plan the race, she's very strong in the finish."