Rio Hondo WTCC: Jose Maria Lopez and Yvan Muller head practice
Citroen's Jose Maria Lopez and Yvan Muller set the pace in World Touring Car Championship practice at the Termas de Rio Hondo track in Argentina on Saturday
Local hero Lopez was quickest of all in the first session, which got under way following a 45-minute delay due to the pilot of the medical helicopter arriving late after weather conditions hampered his journey to the circuit.
The current championship leader was quick from the off and demoted Muller from the top of the timesheets with his first flying lap with a time of 1m45.505s.
Lopez then made further improvements and managed to whittle it down to 1m43.889s, to become the only driver of the day to dip below the 1m43s barrier.
Team-mate Sebastien Loeb was his closest rival in the first session and ended up 0.260 seconds adrift, having constantly set the quickest time in the first sector but unable to hook up the perfect lap to go top.
The three Citroens were split by Mehdi Bennani, who found late gains in his Proteam Honda Civic to go third, ahead of reigning champion Muller, while Gabriele Tarquini was the fastest of the factory Hondas in fifth.
It looked like Lopez would also top the second session as he went quickest in the early running, but in the final 10 minutes of final practice, Muller managed to pull out a lap of 1m44.214s to put him ahead of his Citroen team-mate.
They maintained their positions until the end, while Tom Chilton found speed in the dying moments to put his ROAL Chevrolet third and just 0.071s off the ultimate pace.
Nine-time World Rally champion Loeb finished fourth. Tarquini was the fastest Honda in fifth, just ahead of team-mate Tiago Monteiro, and Hugo Valente and Nobert Michelisz occupied seventh and eighth in their Campos Chevrolets.
Tom Coronel had a disastrous second session as the Dutchman was forced to pit with smoke bellowing from the rear of his Chevrolet Cruze.
The ROAL mechanics soon extinguished the flames and they now face the challenge of preparing the car ahead of qualifying later on Saturday.
Practice one:Pos Driver Team/Car Time Gap
1. Jose Maria Lopez Citroen 1m43.889s
2. Sebastien Loeb Citroen 1m44.149s +0.260s
3. Mehdi Bennani Proteam Honda 1m44.288s +0.399s
4. Yvan Muller Citroen 1m44.298s +0.409s
5. Gabriele Tarquini Honda 1m44.528s +0.639s
6. Norbert Michelisz Zengo Honda 1m44.675s +0.786s
7. Tiago Monteiro Honda 1m44.719s +0.830s
8. Tom Chilton ROAL Chevrolet 1m45.259s +1.370s
9. Hugo Valente Campos Chevrolet 1m45.302s +1.413s
10. Dusan Borkovic Campos Chevrolet 1m45.541s +1.652s
11. Rob Huff Lada 1m45.541s +1.652s
12. Gianni Morbidelli Munnich Chevrolet 1m45.747s +1.858s
13. James Thompson Lada 1m46.162s +2.273s
14. Tom Coronel ROAL Chevrolet 1m46.197s +2.308s
15. Rene Munnich Munnich Chevrolet 1m46.455s +2.566s
16. Mikhail Kozlovskiy Lada 1m46.617s +2.728s
17. Franz Engstler Engstler BMW 1m50.133s +6.244s*
18. John Filippi Campos SEAT 1m51.655s +7.766s*
19. Camilo Echevarria Engstler BMW *
Practice two:Pos Driver Team/Car Time Gap
1. Yvan Muller Citroen 1m44.214s
2. Jose Maria Lopez Citroen 1m44.254s +0.040s
3. Tom Chilton ROAL Chevrolet 1m44.285s +0.071s
4. Sebastien Loeb Citroen 1m44.364s +0.150s
5. Gabriele Tarquini Honda 1m44.472s +0.258s
6. Tiago Monteiro Honda 1m44.525s +0.311s
7. Hugo Valente Campos Chevrolet 1m44.647s +0.433s
8. Norbert Michelisz Zengo Honda 1m44.737s +0.523s
9. Rob Huff Lada 1m44.981s +0.767s
10. Rene Munnich Munnich Chevrolet 1m45.119s +0.905s
11. Dusan Borkovic Campos Chevrolet 1m45.245s +1.031s
12. Mikhail Kozlovskiy Lada 1m45.435s +1.221s
13. Mehdi Bennani Proteam Honda 1m45.788s +1.574s
14. Gianni Morbidelli Munnich Chevrolet 1m46.146s +1.932s
15. James Thompson Lada 1m46.201s +1.987s
16. Tom Coronel ROAL Chevrolet 1m46.679s +2.465s
17. Franz Engstler Engstler BMW 1m50.781s +6.567s*
18. John Filippi Campos SEAT 1m51.293s +7.079s*
19. Camilo Echevarria Engstler BMW *
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