Having inherited the pole position on the grid after falling three places from Rene Rast, Cassidy led every lap of the race to take a lights-to-flag win at Red Bull Ring, which put Renee as Van der Linde’s main rivals. Rast and Mirko Bortolotti.
At the start of the race Cassidy drove cleanly from pole position to Turn 1 but his front row mate, Nico Muller, was swallowed up by the Abt Audi duo Ricardo Feller and Rust and relegated to fourth.
Cassidy’s teammate, Felipe Fraga, was on the next charge and left it as late as possible to brake in Turn 3, but he got involved in a multi-car mess on the corner exit, suffering a puncture in the final tire in the process.
This allowed sixth-placed Bortolotti to join the fray, as the Grasser Lamborghini driver passed Feller on a frantic opening lap to put himself directly behind title rival Rast.
During the remainder of the first period, Bortolotti shaded the champion’s Audi three times, never separating the two drivers by more than half a second as Cassidy made a comfortable two-second lead at the front of the field.
Rast was the first to make a pit stop – although relatively late by DTM standards – diving into the parking lane at the end of lap 25.
Cassidy and Bortolotti followed suit on the next lap, both completing their mandatory stops together hoping to stay ahead of Rast.
Cassidy was back on the track with a long three-second lead over Rast, but a problem with the front left tire fitting in Bortolotti’s Lamborghini left the Italian with no chance of beating his title rival.
From there, Cassidy took to the checkered flag to score his second straight DTM win, and third for Red Bull at home after Liam Lawson’s double success last year.
Rast finally finished over three seconds on Bortolotti, with the Italian driver having to fend off Mercedes Lucas Auer after stopping.
However, both drivers earned a stack of points on championship leader Van der Linde, who struggled to finish 11th in his Schubert Motorsport BMW.
Rast now faces a 13-point deficit against South Africa by three races, while Bortolotti – who is celebrating his first podium since the summer break – is only 20 points behind in the standings.
Fourth place in the race went to Muller after a long battle with Thomas Preining’s Bernhard Porsche that saw the pair trade multiple times in Turn 3.
In the end, Preining was hit with a 10-second penalty that likely forced Muller off the track to the same right-hand flank, allowing the Audi driver to take fourth.
Abt Audi’s Kelvin van der Linde was one of the last few drivers to complete his stop and jumped to fifth at the finish, before a train of Mercedes cars driven by Maro Engel of GruppeM.
Defending champion Maximilian Goetz finished just behind Engel in his Winward AMG GT3 in seventh, although the two were briefly in a four-way fight with Muller and Brenning for a net fourth place.
Luca Stolz finished eighth with the HRT Mercedes, while a 10-second penalty for speed in the goal lane dropped Gotze’s teammate Lucas Auer from fourth to ninth at the end.
Preining captured the final championship point in 10th after adding 10 seconds to his race time, finishing just over a second short of Sheldon van der Linde.
All BMWs failed to take the lead within the points at Red Bull, with Van der Linde’s teammate Philip Ing only 12th, while Walkenhurst’s only surviving driver Marco Wittmann finished 14th.
The duo of Lawrence Fanthor and Dennis Olsen SSR Porsche have joined Red Bull Ferrari’s Fraga on the list of notable retirees.