Nico Mueller led Porsche driver Laurens Vanthoor in the first practice session for DTM’s season opener at Portimao.
The Swiss driver reeled off a lap of 1:40:793 behind the wheel of the N0. 51 Team Rosberg Audi R8 LMS GT3 Evo II.
That allowed Mueller to surpass the No. 92 SSR Performance Porsche 911 GT3 R driven by Vanthoor.
The Belgian had jumped to the top of timesheets with a personal best lap of 1:41:059.
Mueller then closed in and jumped to second place, before his fastest lap left Vanthoor 0.266 seconds down.
Mirko Bortolotti completed the top three aboard the No. 63 Grasser Racing Team Lamborghini Huracan GT3 Evo, 0.361 seconds down on the fastest time.
Kelvin van der Linde ended the session in fourth for Abt Sportsline.
The South African posted a 1:41:298 behind the wheel of the No. 3 Audi, a lap that was briefly quick enough to top the charts before dropping down.
Dennis Olsen ensured SSR Performance had both of its two cars in the top five, as the Norwegian’s best lap of 1:41:303 beat out the best effort set by Schubert Motorsport’s Philipp Eng by only half a tenth.
Margins during the opening 45-minute session at the Autodromo Internacional do Algarve were tight, with the top ten separated by just 0.645s and a second separating the top 23 cars.
Ricardo Feller jumped to the top of the session minutes in by posting a best time of 1:41.378, but the Swiss driver failed to improve and later slid to seventh.
He remained ahead of the GruppeM Racing Mercedes-AMG GT3 Evo of Maro Engel, who posted a 1:41.402.
Nicki Thiim and René Rast rounded out the top ten for T3 Motorsport and Abt Sportsline, respectively.
All 29 drivers turned laps during the session, which remained green throughout.
Track action at Portimao continues with the second and final free practice session of the weekend at 14:35 p.m. local time.
RESULTS: Practice 1