Powder was kept safely dry in heats leading to semi-finals on the opening morning of racing here at the Paris La Defense Arena. All big contenders made it through but none were ready to show what hey had in their tanks.

Zhang Yufei, of China, led six women on 56s atop the qualifiers in the 100m butterfly, with defending champion Maggie Mac Neil on 57.00 in seventh, the door to the semis closed in 57.90 by Britain's Keanna Macinnes.

Gretchen Walsh, who set the World record at 55.18sec at U.S. Trials last month, went through in fourth on 56.75 but did not get her hand to the wall first in her heat, World junior record holder Mizuki Hirai, of Japan, on 57.71.

In the men's 100m breaststroke, Caspar Corbeau, of the Netherlands, found himself at the helm of heats pace on 59.04, Britain's defending champion Adam Peaty on 59.18.

There was none of the qualification fire we saw in Qin Haiyang on his way to the triple world crown - 50, 100, 200m - in Fukuoka last year: he clocked 59.98 for 9th place - but was safely through.