The main Sepang MotoGP test got off to a busy start on Tuesday morning with many riders heading straight out on track due to the risk of rain.
After a special two-day test for some CRT entries using the new standard ECU, blighted by bad weather and technical gremlins, this morning marked the start of the official three-day test open to all 24 MotoGP riders (plus test riders).
Overnight rain meant a damp track at day break, but the circuit was dry enough for slicks when the green lights were illuminated at 10am.
Valentino Rossi, denied dry track time on his 1000cc Yamaha test debut in November, was among the first out on track.
By 10:30am almost all riders had triggered the timing beam and the first hour ended with Repsol Honda's Dani Pedrosa setting the pace.
However Yamaha's reigning double MotoGP champion Jorge Lorenzo went 0.178s faster with a 2m 2.181s lap early in the second hour of track time.
Gresini's Alvaro Bautista - who took part in a private Honda test alongside Marc Marquez at Sepang last November - then nudged Pedrosa to third in an all-Spanish top three.
The official Sepang race lap record is a 2m 2.108s lap by Casey Stoner, although the newly retired Australian set a 1m 59.607s in last year's pre-season tests.
Rossi - one of the first to record more than ten laps - had briefly moved into second place, before being pushed back to a close fourth (+0.264s) just before the close of the first hour.
Star rookie Marquez was the last factory rider on track, but swiftly rose to fifth place (+0.762s) by 11:10am.
Tech 3 Yamaha's Cal Crutchlow and LCR Honda's Stefan Bradl complete the top seven, but both are over one second from Lorenzo.
Aspar's Randy de Puniet - who, like the other Aprilia ART riders, is not using the standard ECU - is the quickest CRT rider in twelfth place, 2.9s from Lorenzo.
Ben Spies, making his Pramac Ducati MotoGP debut this week, finished the first hour of track action 14th quickest after his first 12 laps on a Desmosedici.
The Texan has been side-lined since injuring his shoulder during last October's storm-shortened Malaysia Grand Prix.
Clouds are still present over the circuit, but it remains dry. Testing is due to conclude at 6pm.