Althea Aprilia's Davide Giugliano topped the timing charts on the opening day of the World Superbike test at Jerez on Monday, which was blighted by wet weather once again.
Riding the RSV4 for the first time following Althea's switch from Ducati over the winter, Giugliano posted the fastest lap during a small window of opportunity towards the end of a mostly-wet session to take the top spot by 0.419s from Marco Melandri on the BMW S1000RR.
Sylvain Guintoli, who has joined Eugene Laverty in the factory Aprilia team for 2013, was third fastest, 2.3s behind Giugliano, with Leon Camier next on the FIXI Crescent Suzuki.
Laverty finished day one of the Spanish shakedown in fifth position, 2.8s behind Giugliano, with Chaz Davies (BMW) and series rookie Jules Cluzel on the second FIXI Crescent Suzuki completing the first seven.
Pata Honda duo Leon Haslam and Jonathan Rea were eighth and ninth respectively, with Ulsterman Rea reporting problems with the new electronics upgrade on his CBR1000RR Fireblade.
Rea's quickest lap was 4.3s behind the Aprilia of Giugliano, underlining the extent of the teething issues he is experiencing with the Honda's new electronics.
Kawasaki's Tom Sykes and Loris Baz are also testing at Jerez but elected to ride without transponders and no times were therefore available for either rider.
Poor weather has blighted testing at Jerez, with Alstare Ducati's Carlos Checa and Ayrton Badovini managing less than three hours' track time on their new Panigale 1199R machines during a separate three-day test from Saturday to Monday.
Meanwhile, in the World Supersport class British rider Sam Lowes set the pace on his Yakhnich Motorsport Yamaha R6.
Lowes was 0.7s ahead of impressive newcomer Jack Kennedy from Dublin on the Rivamoto Honda.
Irishman Kennedy, who finished as the runner-up in the British Supersport Championship in 2012, is competing for the Russian outfit under the guidance of former Grand Prix rider Jeremy McWilliams this year.
Reigning champion Kenan Sofuoglu (Kawasaki) was third fastest, 0.9s down on Lowes, whose fastest lap put him sixth overall on the weather-influenced combined Superbike and Supersport timesheets, 3.5s slower than Althea Aprilia pace-setter Giugliano.