Cal Crutchlow led the new free practice four session at Qatar on Saturday night, which immediately precedes the start of the new qualifying format.
The Englishman set the fastest lap of the weekend with a 1m 55.655s to put his Monster Yamaha Tech 3 machine 0.342s clear of Friday pace setter Marc Marquez (Repsol Honda).
Factory Yamaha team-mates Jorge Lorenzo and Valentino Rossi were third and fourth, followed by LCR Honda's Stefan Bradl and top Ducati rider Andrea Dovizioso (+0.723s).
Marquez's team-mate Dani Pedrosa was again down the timesheets in seventh, followed by Americans Nicky Hayden and Ben Spies.
Spies was dumped hard onto his left shoulder during a lowside fall with nine minutes to go. Fortunately, last year's surgery, from which he is still recovering. was carried out on the other shoulder.
The FP4 session has been added for 2013, due to the change in qualifying format.
Instead of the previous one hour of traditional qualifying, the new system - making its debut tonight - sees the hour divided into a 30 minute FP4 session, for all competitors, then Qualifying 1 and Qualifying 2, each lasting 15 minutes.
The ten fastest riders after third practice have already secured their place in Q2, while the others - including Pramac Ducati riders Andrea Iannone and Spies - will fight over the remaining two places available in Q1.