Jorge Lorenzo Sepang test 2012Jorge Lorenzo marked his return to the track after last year's injury with the fastest time in the first preseason MotoGP test at Sepang, while reigning champion Casey Stoner sat out the session with back pain.

Stoner aggravated an old back injury while warming up before going out this morning. After receiving physiotherapy, he decided to wait until tomorrow before taking to the track, with Honda test rider Kousuke Akiyoshi doing a handful of laps on his bike instead.

At the front, Yamaha rider Lorenzo set the pace with a lap of 2m01.657s, 0.2sec slower than last year's pole time at the Malaysian Grand Prix venue, and 0.346sec ahead of second-placed Dani Pedrosa's Honda. 2010 champion Lorenzo was making his first appearance for Yamaha since his '11 campaign was ended prematurely by a serious hand injury sustained at Philip Island.

Yamaha had three bikes in the top four, with Tech 3 rider Cal Crutchlow impressing in third place and Ben Spies putting the second factory bike fourth. Crutchlow's new teammate Andrea Dovizioso was sixth as he got back up to speed after breaking his collarbone in a recent motocross accident.

Valentino Rossi took an encouraging fifth on the best of the Ducatis, 0.7sec off the pace, and 0.8sec quicker than teammate Nicky Hayden – another man recovering from a winter injury.

A handful of the new CRT bikes were present, but a long way off the pace, with Forward Racing's Colin Edwards 6.6sec down on Lorenzo on his Suter-BMW, although he did lose mileage to electrical problems. The Avintia FTR-Kawasakis of Jordi Torres and Ivan Silva were several seconds slower still.

Fellow CRT squads Aspar and Speed Master had already begun testing in a private session at Valencia on Monday, where Aspar's Randy de Puniet was quickest on 1m35.3s – 3.5sec slower than the 2011 MotoGP pole time.

Pos  Rider               Team/Bike             Time       Gap       Laps
 1.  Jorge Lorenzo       Yamaha                2m01.657s            30
 2.  Dani Pedrosa        Honda                 2m02.003s  + 0.346s  48
 3.  Cal Crutchlow       Tech 3 Yamaha         2m02.221s  + 0.564s  32
 4.  Ben Spies           Yamaha                2m02.234s  + 0.577s  28
 5.  Valentino Rossi     Ducati                2m02.392s  + 0.735s  43
 6.  Andrea Dovizioso    Tech 3 Yamaha         2m02.751s  + 1.094s  20
 7.  Hector Barbera      Pramac Ducati         2m02.773s  + 1.116s  41
 8.  Katsuyuki Nakasuga  Yamaha                2m02.829s  + 1.172s  32
 9.  Alvaro Bautista     Gresini Honda         2m02.869s  + 1.212s  45
10.  Nicky Hayden        Ducati                2m03.151s  + 1.494s  33
11.  Stefan Bradl        LCR Honda             2m03.668s  + 2.011s  44
12.  Karel Abraham       Cardion Ducati        2m03.781s  + 2.124s  45
13.  Franco Battaini     Ducati                2m04.986s  + 3.329s  35
14.  Kousuke Akiyoshi    Honda                 2m07.163s  + 5.506s  4
15.  Colin Edwards       Forward Suter-BMW     2m08.240s  + 6.583s  21
16.  Jordi Torres        Avintia FTR-Kawasaki  2m10.671s  + 9.014s  42
17.  Ivan Silva          Avintia FTR-Kawasaki  2m11.267s  + 9.610s  12