Zuzana Hejnova in the opening round of the 400m Hurdles (© Getty Images)
World 400m Hurdles leader Kaliese Spencer, who just missed out on a medal at the last Championships, sent an early message in the first heat that not only is she looking for an improvement on that position but is in shape to grab the gold medal.
As good as the former World junior champion is and her excellent pre-Championships season which includes three victories in the Samsung Diamond League series where she is defending her overall title, she is fully aware it won't be a cakewalk to the title.
The 24-year-old realises that fellow Jamaican Melaine Walker although not looking brilliant in her qualifier, is fully geared up to defending her title while Lashinda Demus a two-time silver medallist is equally determined on this occasion to take home a golden one.
Spencer set the competition in motion when a clear leader after the second hurdle she claimed the opening heat in a time of 54.93 ahead of Ukrainian Anastasiya Rabchenyuk, fourth at the last Olympics, and the USA's former NCAA champion Queen Harrison.
The second heat produced an equally convincing display from Czech record holder Zuzana Hejnova who came to Daegu 2011 with the second fastest time in the world this year.
With SDL victories under her belt in Oslo and Paris - where she relegated Spencer to second place - the 24-year-old was much slower in 55.13 but sensibly eased down well before the finish ahead of Russia's Yelena Churakova and Belgium's Elodie Ouedraogo.
Ouedraogo a former sprinter with Olympic silver and World bronze 4x100m Relay medals to her credit, lowered her personal best to 55.40 a time she shared with fourth finisher Ukrainian Hanna Titimets.
Demus was next in action and in typical style which is the American star's forte went off very quickly to cross the line and match the time which Spencer had achieved. European bronze medallist Perri Shakes-Drayton of Great Britain and Ukrainian Anna Yaroshchuk the recently crowned World Student Games champion followed her home.
Bulgaria's Vania Stambolova last summer's European silver medallist and a former Area champion over the 400 flat, claimed the fourth heat in 55.29 with Ristananna Tracey, the second fastest junior of all-time, and Eilidh Child of Great Britain in the minor positions.
Walker, running in lane seven, was the last of the favourites in action and the defending champion and reigning Olympic gold medallist commencing the start of a chase for a third global title in three years, didn't look too composed.
The 28-year-old, after initially discharging the challenge South Africa's Wenda Theron gave her until the halfway point, then made a mess of the last hurdle allowing Russian champion Natalya Antyukh to get almost alongside.
But Walker quickly gathered her wits and got to the line first in 54.86, 0.02 ahead of the former Olympic 400m flat bronze medallist with Theron setting a personal best of 56.13 for third.
That proved to be the fastest time of the day and a good rehearsal for Tuesday's semi final. Walker shaking her head after having to respond to Antyukh's late challenge knows at that vital point any mistakes will be costly.
Lauren Lee and David Martin for the IAAF
