Marco Melandri appeared to confirm solutions found during the post-race Imola test by leading the timesheets during opening practice for this weekend\'s Assen World Superbike round. The BMW star, who took a fourth place on his Dutch WSBK debut as a Yamaha rider in last year\'s event, starts this weekend having slipped from second to fifth in the standings after his podium absence at Imola. The former MotoGP rider, who claimed his first ever grand prix victory in the 1998 Dutch 125cc TT, fired out a 1m 37.582s best (+1.5sec from the race lap record) on the penultimate of his 17 circulations in the Friday morning session. The Italian was only 0.129s ahead of reigning champion and 2012 points leader Carlos Checa (Althea Ducati) with lone factory Kawasaki rider Tom Sykes making it three riders within 0.2s at the head of the timesheets. An excellent start for the S1000RR riders was completed by Michel Fabrizio, Leon Haslam and Ayrton Badovini, who made it four BMWs in the top seven. Jonathan Rea of the home Ten Kate Honda team was sandwiched between the trio in fifth (+0.586s). Eugene Laverty (Aprilia), Niccolo Canepa (Red Devils Ducati) and Maxime Berger (Effenbert Ducati) completed a top ten covered by 0.9s, while Davide Giugliano (Althea Ducati) and Leon Camier (Crescent Suzuki) were the final riders within a second of Melandri. The healing John Hopkins was just behind team-mate Camier in 13th, while former champion and Checa\'s nearest challenger Max Biaggi was only 17th quickest (+1.346s) on his factory RSV4. ParkinGO Aprilia rookie Chaz Davies, who took his first WSS win at the track last season and went on to claim the title, began the weekend 21st out of the 23 riders.