Works Yamaha rider Marco Melandri has set his World Superbike stall out early, taking top spot in the opening free practice session at Motorland Aragon but is less than a tenth of a second faster than series leader Carlos Checa while BMW's Ayrton Badovini is a surprise third.
Melandri and Checa are the only two men to do sub two minute times, with the Italian on a 1'59.822 and the Spaniard going round in 1'59.917. Badovini is the best part of half a second further back while Alitalia Aprilia's Leon Camier was fourth on a 2'00.334.
After the initial jousting was over and Biaggi, Haga and Lascorz had picked themselves up off the floor, Alstare Suzuki's Michel Fabrizio headed the timesheets with a 2'01.314 before Checa put the hammer down and was the first to go under the 2'01 barrier with a 2'00.346, a time which stood until only 15 minutes was left on the clock.
It was then Melandri stepped up to put in a 1'59.837 as Badovini nudged Checa into third but the Spaniard was having none of it, coming back just moments later with a 2'00.152 while Camier sat in fourth place. Melandri then upped the pace again to a 1'59.822 and Checa had no answer, settling for his 1'59.917 as Badovini and Camier also could find no more speed.
PBM Kawasaki's Tom Sykes shot into fifth place with his last lap and is only one one-hundredth slower than his compatriot while Fabrizio slipped to sixth but is still ahead of Biaggi who won't have done his foot injury any favours by crashing.
Jakub Smrz has found some consistency this season as he popped his Liberty Ducati into eighth just ahead of Maxime Berger while Eugene Laverty, who had been third fastest early on, rounds out the top ten. Haga is 11th and 1.2s off the pace while Leon Haslam is having a minor disaster down in 14th.
Read Colin Wright's views on why catching Checa isn't rocket science
