Ducati rider Casey Stoner won an exciting duel with 2010 MotoGP world championship leader Jorge Lorenzo to top the timesheets at the end of a rain-hit second practice session at the Motorland Aragon track.
World championship leader Lorenzo and Stoner exchanged the lead several times in a session that was run in full wet conditions after a heavy downpour just as the 45-minute session was due to commence.
Dani Pedrosa, who was quickest in the dry this morning, made the early running, but Stoner first moved to the top of the leaderboard with just over 30 minutes remaining.
Pedrosa briefly seized back the initiative but he eventually finished in a lowly 13th position, a best lap of 2.05.394 leaving him over 3.5s off the pace. Only Mika Kallio, Aleix Espargaro and Hiroshi Aoyama were slower than Pedrosa with the Spaniard struggling in his 13-lap stint.
Lorenzo looked to have done enough to secure top spot on his factory Yamaha YZR-M1 when he posted a best lap of 2.02.340 in the final four minutes, That put the 23-year-old 0.325s ahead of Stoner’s factory Ducati GP10, but the 2007 world champion wasn’t finished.
A lap of 2.02.446 cut the gap to just 0.168s and he claimed top spot with a blistering 2.01.710 on his final lap of the impressive Motorland Aragon track.
That put Stoner, who hasn't won a premier class race for 11 months, 0.568s clear of Lorenzo who had bettered his time to 2.02.278 to drop Nicky Hayden back down to third.
Hayden logged a 2.02.411 to finish 0.701s behind Stoner but the American has made an excellent start to the inaugural Motorland Aragon race having been second quickest in dry conditions this morning.
Reigning world champion Valentino Rossi was fourth fastest in the rain with a 2.02.878 leaving the 31-yea-old 0.467s behind Hayden.
Marco Melandri was a surprise fifth as he made use of the miserable conditions to force his way into contention. The Italian, who will partner Eugene Laverty in Yamaha’s World Superbike squad next season, logged a 2.03.146 to finish 0.268s behind Rossi.