Defending Olympic champions Jessica Fox of Australia and Jiri Prskavec of Czechia both safely made the semifinals in their respective heats on a hot afternoon of canoe slalom at the Vaires-sur-Marne Nautical Stadium on Tuesday.

Though the champions both thrilled the crowd with their skillful racing, the biggest cheers were reserved for France's Titouan Castryck, who made a brace of lightning-quick descents in front of his home crowd in the men's kayak heats to qualify in first place.

With the temperature well over 30 degrees, medical and safety staff took hats and t-shirts from those in the stands during the breaks in the action and dipped them in the water before passing them back in an effort to keep the fans cool.

Fox, who won gold in the single kayak event on Sunday at the Paris Games, started superbly in the women's single canoe event and eased off in the second part of the course to come home second in 100.05 seconds, just behind Czech Gabriela Satkova.

Tokyo silver medalist Mallory Franklin of Britain also made it through to the semis thanks to a first-run time of 104.72.

Pedro Goncalves of Brazil set the early pace in the men's kayak but it was Castryck who got the crowd off their feet, recording a stunning first run of 83.71 seconds before going even faster on his second descent, finishing in a time of 80.09.

British 2016 gold medalist Joe Clarke bounced back from a 50-second penalty on his first run with an excellent second try, completing the course in 85.62 seconds to jump into fourth place.

Last out, world No. 1 Prskavec lashed through the course but slowed down after the final gate to take second spot after his first run to book his spot in the semis.

The women's canoe semifinals and final takes place on Wednesday, while the men's kayak medals will be decided on Thursday.