Dani Pedrosa edges title rival Jorge Lorenzo in first practice at Brno

The two Spaniards are effectively the only men in contention for this year's world championship following Casey Stoner's decision to leave Brno and fly home for ankle surgery.

There was little to choose between the pair in the opening practice session of the Czech Grand Prix, although Pedrosa's best of 1m59.003s was ultimately enough to earn him top spot, just over one tenth of a second ahead of Lorenzo.

There was a moment of drama for the Honda man however, as a stone thrown up when Valentino Rossi ran wide and through the dirt hit him on the foot.

He was visibly limping as he headed back into the pits and pulled into his garage, although he was later able to rejoin the track and set his fastest time.

The debris churned up by Rossi's Ducati also caused a brief red flag session to clear the circuit.

When it did resume, the two Tech 3 Yamaha bikes managed to close on the lead pair, with Andrea Dovizioso - who will move to Ducati from 2013 - heading team-mate Cal Crutchlow.

Ben Spies completed a happy session for Yamaha by taking fifth on the second works bike, less than half a second down on Pedrosa.

Gresini Honda's Alvaro Baustita also got within five tenths of the Spaniard, while Valentino Rossi in seventh finished 1.168s down.

LCR Honda rider Stefan Bradl finished eighth, ahead of the CRT duo of Randy de Puniet (Aspar) and Yonny Hernandez (Avintia).

Alongside Stoner, Ducati's Nicky Hayden and Pramac's Hector Barbera will miss this weekend due to injuries suffered at Indianapolis.

Pos  Rider             Team/Bike                 Time       Gap
 1.  Dani Pedrosa      Honda                     1m57.003s
 2.  Jorge Lorenzo     Yamaha                    1m57.149s  + 0.146s
 3.  Andrea Dovizioso  Tech 3 Yamaha             1m57.189s  + 0.186s
 4.  Cal Crutchlow     Tech 3 Yamaha             1m57.418s  + 0.415s
 5.  Ben Spies         Yamaha                    1m57.446s  + 0.443s
 6.  Alvaro Bautista   Gresini Honda             1m57.501s  + 0.498s
 7.  Valentino Rossi   Ducati                    1m58.171s  + 1.168s
 8.  Stefan Bradl      LCR Honda                 1m58.345s  + 1.342s
 9.  Randy de Puniet   Aspar Aprilia             1m58.667s  + 1.664s
10.  Yonni Hernandez   AvintiaFTR-Kawasaki       1m59.256s  + 2.253s
11.  Karel Abraham     Cardion Ducati            1m59.256s  + 2.253s
12.  Aleix Espargaro   Aspar Aprilia             1m59.504s  + 2.501s
13.  Toni Elias        Pramac Ducati             1m59.881s  + 2.878s
14.  Mattia Pasini     Speed Master Aprilia      2m00.206s  + 3.203s
15.  Colin Edwards     Forward Suter-BMW         2m00.531s  + 3.528s
16.  Michele Pirro     Gresini FTR-Honda         2m00.715s  + 3.712s
17.  Ivan Silva        Avintia Inmotec-Kawasaki  2m01.302s  + 4.299s
18.  James Ellison     Paul Bird Aprilia         2m02.171s  + 5.168s
19.  Danilo Petrucci   Ioda-Aprilia              2m02.244s  + 5.241s