Those hoping that his coronation may have given Lopez cause to back off were to be quickly disappointed in first practice, as he hurled his C-Elysee to a fastest time of 2m03.453s.
Lopez's nearest rival was Mehdi Bennani, the Moroccan carrying over his impressive pace from the morning's testing session to set the second best time, 0.410 seconds back from Lopez.
Sebastien Loeb completed an all-Citroen top three with a best effort of 2m03.068s, while Stefano D'Aste was an encouraging fourth in his Munnich Motorsport Chevrolet Cruze, marginally ahead of Honda's Gabriele Tarquini.
Loeb's nearest challenger for second place in the championship, Citroen team-mate Yvan Muller, managed only the ninth-fastest time.
There was no let up from Lopez in the second session as the Argentinian went more than a second faster than anyone else with his opening gambit, before becoming the first man to dip below the 2m02s barrier with a 2m01.859s on his second attempt - which would end up being the fastest lap of the session.
Campos Racing's Hugo Valente got closer than anyone else to Lopez with an effort on 2m02.084s, while Gregoire Demoustier was a surprise third in his Craft-Bamboo Chevrolet Cruze.
Loeb ended up fourth and second-best of the Citroens, with Ma Qing Hua, Bennani and Muller finishing seventh, eighth and 11th respectively.
Nasser Al-Attiyah continued to find time on his WTCC debut in the third Campos Chevrolet Cruze, finishing the second session in 17th place, 1.741s slower than Lopez.
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