After the opening day's practice at Aragon for the fifth round of the World Superbike Championship five-time world champion Jonny Rea was edged out of pole position by a mere one thousandth of a second by Italian Michael Rinaldi on an independent Ducati, the only two riders in both sessions to dip into the 1m 49sec bracket.
Rea's Kawasaki team mate Alex Lowes was third fastest, half a second behind the front two.
Scott Redding, 10 points adrift of Rea in the championship chase, was in ninth position, a second down on his rival, having suffered technical issues with his factory Ducati Panigale V4.
Eugene Laverty was in twelfth position on the factory BMW with his team mate Tom Sykes fourth in the combined times of the two 50-minute sessions where less than a second covered the top eight riders.
Rea said, "In FP2 we stuck to the plan to do a long run on the soft tyre. We did 18-laps and I felt good physically and the tyre consumption was OK. I need to make a big effort in Superpole because track position is everything here. If I start from the front row, I may be able to dictate the pace a little bit better."
Gino Rea, standing in for the injured Keith Farmer, on the Buildbase Suzuki topped the opening British Superbike Championship free practice session around the short 1.640mile Silverstone National circuit with a lap of 53.434secs.
Current championship leader, by 23-points, Glenn Irwin (Honda) was second fastest with 0.173sec separating the duo.
Andrew Irwin ended the session in seventh position on his Honda, less than half a second behind Rea, having been down in 13th with 12 minutes of the session remaining.
The combined Supersport times after two sessions saw Bradley Perie top the leaderboard with Lee Johnston and Korie McGreevy three-quarters of a second adrift in third and fifth positions respectively while Alastair Seeley was second fastest in the concurrently ran GP2 class 0.128sec behind championship leader Mason Law.
Omagh's Jamie Lyons was the best of the local runners in the British Talent Cup practice sessions in eleventh position, while Mondello Park backed Rhys Irwin topped the Superstock 600cc class after two sessions in which Simon Reid was fifth fastest, Eugene McManus, Adam McLean and Sam Laffins twelfth, thirteenth and fourteenth respectively.