The race was red-flagged following a chaotic restart on lap 6 that saw Thomas Preining and David Schumacher smashing into the barriers on the run to Turn 8 following contact, and Dennis Olsen hitting the wall rear-first just seconds later after a separate incident with Ricardo Feller.
All cars were heavily damaged in the incident, with the engine from Olsen's Porsche being thrown out of the car on impact and immediately catching fire.
Only 17 out of 27 cars returned on track when the race resumed after a long red flag, as several others had retired earlier in crashes on the opening lap and again on lap 6 prior to the carnage that ensued at Turn 8.
Polesitter Auer was able to hold the lead with ease at the second restart following DTM's decision to abandon the much-maligned double-file restart procedure, with Marco Wittmann closely following the Winward Mercedes driver in his Walkenhorst BMW.
Both drivers headed to the pits at the same time on lap 11, with Auer hanging on to position despite a quicker stop by the Walkenhorst crew.
Wittmann tried to put pressure on Auer on the out lap, but the Austrian was able to withstand the pressure and eventually eke out a one-second buffer over the two-time champion.
Two-time champion Wittmann mounted a second attack on lap 26 and even managed to move his nose ahead of Auer into the hairpin, only to run deep and allow the latter back through into the net lead.
Auer was then able to pass the Rosberg Audi of Dev Gore - who had moved up the order controversially with a pitstop that remains under investigation - to score his first win since the season opener at Portimao.
However, this wasn't enough to take the lead of the championship following an inspired recovery drive from Sheldon van der Linde, who rebounded from a 10-place grid penalty to finish right behind him in second.
The Schubert BMW driver jumped from 16th to eighth at the original start, avoiding the mess that ensued between Turns 1 and 2 as well as the errant wheel thrown off his brother Kelvin's Audi, before charging past his rivals including Rene Rast to move up into the podium positions.
When Wittmann got held up by the struggling Audi of Gore on the penultimate lap, van der Linde sent his BMW up the inside of the German to claim a crucial second position in his pursuit of a maiden title.
Abt Audi's Rast was another driver to make rapid gains on the opening lap, jumping from seventh to third, but was powerless to defend from van der Linde's BMW as he crossed the finish line in fifth behind Gore.
Mirko Bortolotti was the last of the frontrunners to pit after dropping from third to fifth at the original start, but a slow 13.5s pitstop left him tumbling down the order and with a mountain to climb in the remainder of the race.
Bortolotti did manage to regain several positions in the closing stages of the race to finish seventh behind the second Schubert BMW of Philipp Eng, whose result helped the squad clinch the teams' title over Abt Sportsline with a race still to run.
The top 10 was rounded out by Team Rosberg's Nico Muller, Luca Stolz (HRT Mercedes) and Maximilian Buhk (Mucke Mercedes).
Ahead of Sunday's finale, van der Linde leads the championship by two points over Auer, with Rast 21 points adrift in third and Bortolotti 28 in arrears in fourth.
Team Bernhard Porsche driver Preining is effectively out of the title battle following his horrific incident with Schumacher's Winward Mercedes earlier on lap 6.
Race results:
| Cla | # | Driver | Car | Gap |
|---|---|---|---|---|
| 1 | 22 |  Lucas Auer |
Mercedes-AMG GT3 Evo | |
| 2 | 31 |  Sheldon Van Der Linde |
BMW M4 GT3 | 0.681 |
| 3 | 11 |  Marco Wittmann |
BMW M4 GT3 | 1.907 |
| 4 | 12 |  Dev Gore |
Audi R8 LMS Evo II | 3.099 |
| 5 | 33 | René Rast |
Audi R8 LMS Evo II | 5.053 |
| 6 | 25 | Philipp Eng |
BMW M4 GT3 | 5.849 |
| 7 | 63 |  Mirko Bortolotti |
Lamborghini Huracán GT3 Evo | 6.296 |
| 8 | 51 |  Nico Müller |
Audi R8 LMS Evo II | 9.324 |
| 9 | 4 | Luca Stolz |
Mercedes-AMG GT3 Evo | 14.350 |
| 10 | 18 | Maximilian Buhk |
Mercedes-AMG GT3 Evo | 19.652 |
| 11 | 88 | Maro Engel |
Mercedes-AMG GT3 Evo | 20.105 |
| 12 | 3 | Kelvin van der Linde |
Audi R8 LMS Evo II | 21.259 |
| 13 | 74 |  Felipe Fraga |
Ferrari 488 GT3 Evo 2020 | 21.822 |
| 14 | 92 | Christian Engelhart |
Porsche 911 GT3 R | 22.486 |
| 15 | 1 | Maximilian Götz |
Mercedes-AMG GT3 Evo | 31.218 |
| 16 | 10 | Leon Köhler | BMW M4 GT3 | 41.545 |
| 6 | Alessio Deledda |
Lamborghini Huracán GT3 Evo | 11 Laps | |
| 37 |  Nick Cassidy |
Ferrari 488 GT3 Evo 2020 | 24 Laps | |
| 7 | Ricardo Feller |
Audi R8 LMS Evo II | 24 Laps | |
| 24 | Thomas Preining |
Porsche 911 GT3 R | 24 Laps | |
| 27 | David Schumacher |
Mercedes-AMG GT3 Evo | 24 Laps | |
| 94 |  Dennis Olsen |
Porsche 911 GT3 R | 24 Laps | |
| 55 |  Mikael Grenier |
Mercedes-AMG GT3 Evo | 24 Laps | |
| 85 | Clemens Schmid |
Lamborghini Huracán GT3 Evo | 24 Laps | |
| 19 | Rolf Ineichen |
Lamborghini Huracán GT3 Evo | 24 Laps | |
| 66 | Marius Zug |
Audi R8 LMS Evo II | 24 Laps | |
| 36 |  Arjun Maini |
Mercedes-AMG GT3 Evo | ||
| View full results | ||||
