Liqui Moly Team Engstler driver Charles Ng spun off at and hit the barriers at the Della Roggia chicane, damaging the front of his BMW 320 TC but he was able to return to the pits.
The first part of qualifying saw multiple incidents with reigning champion Robert Huff colliding Fredy Barth less than three minutes into the session.
When the session resumed, the two Ladas collided with Aleksei Dudukalo missed the braking point for the first chicane and went straight into the side of Thompson's car.
Honda driver Gabriele Tarquini tapped René Münnich into a spin just before the end of the session and the getting a black and white flag.
After repairs, Thompson was able to get out in the second session to finish ninth and a front row start on the reversed grid for race two behind the ROAL Motorsport car of Darryl O'Young.
At the end of the ten-minute shoot–out Muller led an RML 1–2 with Chilton second and MacDowall third the leading independent driver in the Bamboo Chevrolet.
The best placed ALL-INKL.COM Münnich Motorsport driver Marc Basseng was eighth on his debut in the World Touring Car Championship.
Further up the field Basseng and Tarquini engaged in battle for 6th place before the safety car came out at the end of the lap 5 while the stricken BMW of D'Aste was removed.
By lap eight Huff had made his way up the field to tenth place, displacing Tom Boardman from the final points position.
The race was completed with yellow flags in the second sector, Muller took the first win of the season with Chilton second to take his first podium result in the WTCC.
Dayraut, Mehdi Bennani, Fernando Monje and MacDowall all took the escape round at the first chicane on lap three due to the slippery conditions at the end of the pit straight.