Marc Marquez takes over at the top in FP2 - riding as hard as ever over the kerbs, kicking the rear out under braking and running wide on a few occasions.
Marquez and Repsol Honda team-mate Dani Pedrosa rode together during the closing stages when they each set their best times to claim first and second, each using the hard rear tyre.
Aleix Espargaro took third with the special Open class soft rear tyre fitted to his Forward Yamaha.
Ducati's Andrea Dovizioso recovered from a big engine failure early in the session. Pramac Ducati's Andrea Iannone likewise returned after a heavy fall when his rear wheel appeared to lock at the end of the back straight.
Morning leader Jorge Lorenzo dropped to ninth place for Movistar Yamaha, over two-seconds behind Marquez.
MotoGP is returning to Argentina for the first time since 1999 and making its race debut at the Termas de Rio Hondo circuit.
Stefan Bradl (LCR Honda), Alvaro Bautista (Gresini Honda), Cal Crutchlow (Tech 3 Yamaha) and Hector Barbera (Avintia) attended a dirty and damp two-day test at the circuit last July.
Crutchlow, now at Ducati, is absent this weekend due to hand injuries sustained in Austin. The Englishman has been replaced by factory test rider Michele Pirro.
for pictures from the grand prix...
1. Marc Marquez
ESP Repsol Honda Team (RC213V) 1m 39.313s [Lap 16/18] 325km/h
2. Dani Pedrosa
ESP Repsol Honda Team (RC213V) 1m 40.396s +1.083s [18/18] 326km/h
3. Aleix Espargaro
ESP NGM Forward Racing (Forward Yamaha) 1m 40.566s +1.253s [15/16] 320km/h
4. Stefan Bradl
GER LCR Honda MotoGP (RC213V) 1m 40.891s +1.578s [18/20] 326km/h
5. Andrea Dovizioso
ITA Ducati Team (Desmosedici) 1m 41.042s +1.729s [5/11] 328km/h
6. Bradley Smith
GBR Monster Yamaha Tech 3 (YZR-M1) 1m 41.303s +1.990s [16/20] 324km/h
7. Pol Espargaro
ESP Monster Yamaha Tech 3 (YZR-M1)* 1m 41.368s +2.055s [14/19] 322km/h
8. Valentino Rossi
ITA Movistar Yamaha MotoGP (YZR-M1) 1m 41.395s +2.082s [17/21] 323km/h
9. Jorge Lorenzo
ESP Movistar Yamaha MotoGP (YZR-M1) 1m 41.533s +2.220s [9/18] 324km/h
10. Andrea Iannone
ITA Pramac Racing (Desmosedici) 1m 41.924s +2.611s [11/13] 324km/h
11. Alvaro Bautista
ESP Go&Fun Honda Gresini (RC213V) 1m 42.029s +2.716s [12/20] 326km/h
12. Yonny Hernandez
COL Pramac Racing (Desmosedici) 1m 42.128s +2.815s [14/16] 320km/h
13. Karel Abraham
CZE Cardion AB Motoracing (RCV1000R) 1m 42.348s +3.035s [14/18] 317km/h
14. Colin Edwards
USA NGM Forward Racing (Forward Yamaha) 1m 42.608s +3.295s [15/19] 313km/h
15. Nicky Hayden
USA Drive M7 Aspar (RCV1000R) 1m 42.621s +3.308s [14/18] 311km/h
16. Hector Barbera
ESP Avintia Racing (Avintia) 1m 42.739s +3.426s [12/16] 308km/h
17. Broc Parkes
AUS Paul Bird Motorsport (PBM-ART)* 1m 42.827s +3.514s [14/14] 302km/h
18. Michele Pirro
ITA Ducati Team (Desmosedici) 1m 42.898s +3.585s [15/17] 318km/h
19. Danilo Petrucci
ITA IodaRacing Project (ART) 1m 43.106s +3.793s [14/18] 307km/h
20. Mike Di Meglio
FRA Avintia Racing (Avintia)* 1m 43.125s +3.812s [7/14] 309km/h
21. Michael Laverty
GBR Paul Bird Motorsport (PBM-ART) 1m 43.151s +3.838s [14/17] 307km/h
22. Scott Redding
GBR Go&Fun Honda Gresini (RCV1000R)* 1m 43.165s +3.852s [15/16] 307km/h
23. Hiroshi Aoyama
JPN Drive M7 Aspar (RCV1000R) 1m 43.347s +4.034s [12/18] 311km/h
Blue Name = Factory - Control ECU hardware, unique manufacturer software.
20 litres of race fuel, 5 engine changes for the season. All engines identical throughout the year within the same team (development freeze).
Black Name = Factory (with concessions) - Control ECU hardware, unique manufacturer software.
Applicable to Factory entries by a manufacturer that did not achieve a dry win in 2013 (only Ducati) plus any new MotoGP manufacturers.
Same 24 litres of race fuel, 12 engine changes, softer rear tyre, no engine development freeze and extra testing opportunities as the Open Category. Fuel to be reduced to 22 litres should Ducati achieve a race win, two second places or three (dry) podiums. If Ducati claims three wins they will also lose the softer rear tyre. All other concessions confirmed until start of single ECU era in 2016.
Red Name = Open - Full control ECU system, hardware and software.
24 litres of race fuel, 12 engine changes, softer rear tyre, no engine development freeze and greater testing opportunities relative to Factory.
Fastest FP1 lap:
ESP Yamaha 1m 42.804s
Fastest lap at July 2013 test:
GER Honda 1m 44.188s
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