Wet weather tyres finally got some proper airtime in a soaked Le Mans and the conditions seemed to even out the field even more, with the lead changing hands on every other lap but unlike their lightweight class colleagues, there was no action whatsoever in the gravel trap. The timesheets were an unusual sight at the end of FP1, with Bradley Smith snatching the lead at the checkered flag, a tenth of a second faster than the Ducati invasion led by Johann Zarco. Another of the late leaders, Danilo Petrucci occupied third spot, ahead of colleagues Jack Miller and Andrea Dovizioso.
Maverick Vinales in sixth was the final rider to post a time within half a second of the lead, followed by Yamaha colleagues Franco Morbidelli and Valentino Rossi. Despite still struggling with his recovery from surgery, Cal Cructhlow climbed into ninth as the top Honda machine, while early leader Pol Espargaro dropped to tenth in the closing stages of practice.
The likes of Pecco Bagnaia, Alex Rins and Joan Mir missed out on the top ten and finished one second slower than the leader. Championship leader Fabio Quartararo did not seem too keen to take risks in the wet and finished the session 18th, over two and a half seconds down on the leading Aprilia.