Can Oncu topped rain-affected FIM Supersport World Championship Free Practice One (FP1) Friday morning at TT Circuit Assen, in The Netherlands.
Riding his Puccetti Racing Kawasaki Ninja ZX-6R around the 2.8-mile (4.5 km) road course, the Turkish racer turned a lap time of 1:44.919 early in the session, before the rain intensified.
Niki Tuuli was second with a 1:46.355 on his EAB Racing Team Ducati Panigale V2, and Ondrej Vostatek rounded out the top three with a time of 1:47.521 on his PTR Triumph Street Triple RS 765.
Former MotoAmerica Supersport regular Valentin Debise finished the wet session 25th with a 1:56.143 on his Evan Bros. Yamaha YZF-R6.