Olympic champion Jason Kenny`s Parisian nightmare ended in abject failure on Saturday as the Briton was knocked out in the first round of the men`s sprint.
Having finished 10th in qualifying, he was then beaten by Hersony Canelon of Venezuela.
At the national velodrome in Saint-Quentin-en-Yvelines, just outside the French capital, he had also lost in the first round of the keirin and finished eighth in the team pursuit.
For a three-time Olympic gold medal winner and twice world champion, his competition has been an unmitigated disaster.
Reigning champion Francois Pervis had to come through the repechage to keep his sprint repeat hopes alive.
Pervis had been beaten in the eighth-finals by French compatriot Quentin Lafargue.
But last year`s silver medallist Stefan Boetticher, was knocked out, beaten by 2014 bronze medallist Denis Dmitriev of Russia in the eighth-final before the German finished behind Pervis in the repechage.
World record holder Jack Bobridge of Australia qualified for the evening`s individual pursuit final by recording the fastest time in qualifying over the 4km course.
Bobridge, the 2011 champion, will meet last year`s runner-up Stefan Kueng of Switzerland for the gold medal.
Australia`s reigning champion Alex Edmondson had been on course to join Bobridge in the final until the final kilometre when he cracked to finish eighth.
Olympic champion Laura Trott and world champion Sarah Hammer both had a slow start to the women`s omnium -- the six-discipline event.
Trott finished down in 13th in the opening scratch race before winning the individual pursuit to move up to seventh overall.
Hammer was eighth in the scratch before a fourth place finish in the pursuit left her in the same position overall.
Annette Edmondson, part of Australia`s world record-breaking team pursuit squad, was the overall leader after two disciplines ahead of Belarussian Tatsiana Sharakova and Kirsten Wild of the Netherlands.
The men`s omnium was shaping up into a battle between two road sprinters.
Young Colombian sensation, Fernando Gaviria, who beat Mark Cavendish twice last month at the Tour of San Juan, held a six-point lead over Italian Elia Viviani, who rides for Britain`s Team Sky.
Viviani has won three of the five events so far with only the points race to come on Saturday evening.
Australian 2012 world champion Glenn O`Shea was third, 12 points behind Gaviria, but 2013 world champion Aaron Gate of New Zealand was 12th and way out of contention after a disastrous 1km time-trial saw him finish last but one.
Reigning champion Thomas Boudat has his work cut out to get among the medals, sitting fifth but 20 points behind O`Shea.