Ohuruogu, the world champion in Osaka six years ago, progressed through her 400m semi-final in emphatic style, clocking a season's best 49.75 seconds, just 0.14 seconds off her personal best.
And the 2008 Olympic champion and London 2012 silver medallist couldn't have been happier, according to coach Lloyd Cowan.
"We absolutely can't take anything for granted tomorrow," he said.
"There are six girls inside 50 seconds and most of them are going to be even closer to the line in the final."
Reigning champion Amantle Montsho, who beat Ohuruogu beat in Birmingham earlier this year, was the most impressive qualifier but her British rival was second quickest - and there is no doubting she is a proven major championship performer.
“I'm just really happy to be in the final. I wanted to make sure I finished well at the end," she said.
Olympic champion Shelly-Ann Fraser-Price leads Jamaica's charge for a 100 metres double at the World Championships following hot on the heels of Usain Bolt's rain-swept victory on Sunday.
Arch rivals Jamaica and the US each have four sprinters through to the semi-finals, including American defending champion Carmelita Jeter.
Nigeria's Blessing Okagbare, who won a long jump silver on Sunday, is ranked second in the world behind Fraser-Pryce and has shown the form to end the 11-year domination of this event by US and Jamaica athletes or at the very least become the first African woman to win a world sprint medal.
The final also takes on Monday when six gold medals will be decided.
The 110 metres hurdlers also have semis and final to negotiate and defending champion Jason Richardson is optimistic of an American sweep of the medals.
"Cleanliness is next to Godliness so it won't matter if we sweep up in the race," he told reporters.
"The track is extremely fast, I'm excited to see what I can do."
World record holder Aries Merritt, fastest man of 2013, David Oliver, and surprise US champion Ryan Wilson complete the American line-up.
Amantle Montsho was the fastest in the semi-finals as she attempts to join Australia's Cathy Freeman as the only women to land back-to-back world 400 titles.
The heptathlon gets underway, with the 100 metres hurdles, high jump, shot put and 200m, minus world champion Tatyana Chernova and Olympic gold medallist Jessica Ennis-Hill who are both injured – with Katarina Johnson-Thompson the main British hope.
France's Renaud Lavillenie is a big favourite for the men's pole vault with the world title the only one missing from his collection.
The Frenchman, who cleared 6.02 metres at the London Diamond League meeting last month, has won at the Olympics, world indoors and European championships indoors and out
The practically invincible Valerie Adams, unbeaten in 38 competitions, goes for a fourth successive world crown in the shot put while in the men's hammer home favourite Sergey Litvinov hopes to go one better than the silver his father managed in the stadium at the 1980 Moscow Olympics.
Key times on day three (UK times)
16:00 – Men’s pole vault final
16:05 – Men’s 110m hurdles semi-finals
16:35 - Women's 100m semi-finals
17:05 - Men's 400m semi-finals
17:25 - Women's shot put final
17:30 - Men's hammer throw final
18:15 – Women’s 400m final
18:30 – Men’s 110m hurdles final
18:50 – Women’s 100m final