Sam Lowes, who suffered a race-stopping accident in last year's Assen World Supersport round, dominated day one of the 2012 event.
The Bogdanka Honda rider, still seeking his first WSS win, led morning practice by just 0.071s over Broc Parkes (Ten Kate Honda), with Lowes' PTR team-mate Jules Cluzel in third.
That order was repeated during the afternoon first qualifying session, when Lowes lowered his best time by over 1.5sec to stay a mere 0.039sec clear of Parkes.
Frenchman Cluzel couldn't quite match the pace of improvements, lapping 0.6sec from Lowes, but still confirmed his place on the overnight front row alongside countryman and championship leader Fabien Foret (Kawasaki Intermoto).
Imola winner and former world champion Foret starts this weekend with a 14-point advantage over Lowes.
Former Assen WSS winner Kenan Sofuoglu (Kawasaki Deltafin) was the final rider within one-second of the top, in fifth. Sofuoglu, still nursing a knee injury, has slipped to third in the championship after being black-flagged at Imola.
Imre Toth, Sheridan Morais, Massimo Roccoli, Mathew Scholtz and Jed Metcher completed the first qualifying top ten.