Rast had qualified third on the grid behind polesitter Timo Glock and Sheldon van der Linde, but a lightning quick start allowed him to dive between the two BMWs and take the lead into Turn 1.
There was further drama for BMW as Glock tagged the WRT Audi of Ferdinand Habsburg, sending both cars straight through the gravel and promoting Mike Rockenfeller to second ahead of van der Linde.
Meanwhile, Robin Frijns was on a charge in the early stages of the race, immediately passing teammate Nico Muller before reeling in van der Linde on Lap 3 to move up to third.
However, the Dutchman’s title hopes took a major blow when exiting the pitlane after coming in for an early stop on lap 11, as he understeered into the barriers as the pit exit turned left to rejoin the track.
The incident caused terminal damage to the Audi's steering rack and he was forced to park the car immediately afterwards, bringing out the safety car.
Rast and Rockenfeller immediately dived into the pits at the end of lap 12 and retained their positions after all drivers had completed their stops.
From there, Rast enjoyed a clear run to the chequered flag, scoring his fourth victory of the season and propelling himself to second in the drivers’ standing ahead of Frijns.
The German driver also cut into the lead of championship leader Muller, who endured a troubled race en route to ninth - his worst race finish of the season.
Abt elected not to pit Muller until after the safety car period was complete, dropping him to eight position in the field.
Despite having the advantage of fresher tyres, Muller was unable to make any inroads and eventually dropped to ninth behind BMW’s Marco Wittmann, who had to come into the pits for a second time as his initial stop didn’t count as his mandatory pitstop.
Lucas Auer finished third for BMW, scoring his first podium finish since his victory at the Lausitzring back in August.
Glock, who had slipped to the last after his lap 1 coming-together with Habsburg, recovered strongly to finish fourth, taking advantage of an early pitstop to gain track position.
The WRT Audis of Fabio Scherer, Harrison Newey and Habsburg likewise benefitted from pitting prior to the safety car, finishing fifth, sixth and seventh respectively.
It marked Scherer’s first points finish of the year, who prior to this race had been the only driver not to finish inside the top 10 in 2020.
Van der Linde bagged the final championship point in 10th, behind Wittmann and Muller.
The ART BMW of Robert Kubica was classified 12th behind the factory BMW of Philipp Eng.
|1|| René Rast ||Audi RS5 Turbo DTM 2020||41||-|
|2|| Mike Rockenfeller ||Audi RS5 Turbo DTM 2020||41||5.400|
|3|| Lucas Auer ||BMW M4 Turbo DTM 2020||41||22.200|
|4|| Timo Glock ||BMW M4 Turbo DTM 2020||41||31.600|
|5|| Fabio Scherer ||Audi RS5 Turbo DTM 2020||41||32.000|
|6|| Harrison Newey ||Audi RS5 Turbo DTM 2020||41||33.700|
|7|| Ferdinand Habsburg ||Audi RS5 Turbo DTM 2020||41||34.300|
|8|| Marco Wittmann ||BMW M4 Turbo DTM 2020||41||40.600|
|9|| Nico Müller ||Audi RS5 Turbo DTM 2020||41||41.100|
|10|| Sheldon Van Der Linde ||BMW M4 Turbo DTM 2020||41||54.200|
|11|| Jonathan Aberdein ||BMW M4 Turbo DTM 2020||41||1'07.900|
|12|| Robert Kubica ||BMW M4 Turbo DTM 2020||41||1.19.3|
|13|| Loic Duval ||Audi RS5 Turbo DTM 2020||41||1 lap|
|14|| Philipp Eng ||BMW M4 Turbo DTM 2020||41||1 lap|
|15|| Jamie Green ||Audi RS5 Turbo DTM 2020||41||1 lap|
|16|| Robin Frijns ||Audi RS5 Turbo DTM 2020||41||30 laps|
|View full results|