Vasser Sullivan Racing’s Aaron Telitz hit the back of Corvette Racing’s Nicky Catsburg at Detroit.
Mostert and Telitz had been a comfortable fourth in the GTD Pro class, 14 seconds off the lead and another 14 seconds clear of their nearest rivals with just under 20 minutes to go.
Debris brought the Safety Car out and bunched the pack, setting up a grandstand finish.
On the restart, Antonio Garcia in the #3 Corvette Racing by Pratt Miller Motorsports Z06 GT3.R led Jack Hawksworth in the #14 Vasser Sullivan Racing Lexus RC-F.
Hawksworth got into the back of the race leader at Turn 3 and was deemed to have made avoidable contact and was given a drive-through penalty.
Moments after that incident, the caution came out for the final time when Nick Tandy buried the #77 AO Racing Porsche 911 GT3 R in a tyre barrier.
Shortly after the final restart, Telitz tried to pass the second-placed #4 Corvette driven by Nicky Catsburg, who blocked under braking into Turn 3.
Telitz ran into the back of Catsburg and suffered damage to the right front corner. Like Hawksworth, Catsburg was given a drive-through penalty for the class.
That promoted Telitz to second, but damage to the #15 Lexus RC-F took them out of contention with a late pit stop.
Ultimately, Garcia and co-driver Alexander Sims clinched the GTD Pro class win.
Pfaff Motorsports duo Andrea Caldarelli and Sandy Mitchell were second in the #9 Lamborghini Temerario. They had been second before the penultimate restart.
Third went to Ford Racing duo factory Christopher Mies and Frederic Vervisch in their Mustang GT3, who also benefited from the late drama having been seventh with 20 minutes to go.
Mostert and Telitz were given a post-race penalty for exiting the pit lane when the red light was showing. They were ultimately not classified.
The outright win went to Earl Bamber and Jack Aitken in the #31 Cadillac Whelen V-Series.R Hypercar.
Despite the late yellows, Aitken was able to stretch his lead to a six-second advantage over the #25 BMW M Team WRT entry of Phillip Eng and Marco Wittmann.
Cadillac bookended the podium with Ricky Taylor and Filipe Albuquerque finishing third in the #10 Cadillac Wayne Taylor Racing car.
Results: IMSA SportsCar Championship Chevrolet Sports Car Class, Detroit Street Course
Pos
Class Pos
Num
Class
Drivers
Team
Car
Laps/Diff
Gap
1
1
31
GTP
J. Aitken / E. Bamber
Cadillac Whelen
Cadillac V-Series.R
82
2
2
25
GTP
P. Eng / M. Wittmann
BMW M Team WRT
BMW M Hybrid V8
6.023
6.023
3
3
10
GTP
R. Taylor / F. Albuquerque
Cadillac Wayne Taylor Racing
Cadillac V-Series.R
6.758
0.735
4
4
93
GTP
R. van der Zande / N. Yelloly
Acura Meyer Shank Racing w/Curb Agajanian
Acura ARX-06
7.341
0.583
5
5
7
GTP
F. Nasr / J. Andlauer
Porsche Penske Motorsport
Porsche 963
8.269
0.928
6
6
40
GTP
J. Taylor / L. Deletraz
Cadillac Wayne Taylor Racing
Cadillac V-Series.R
9.871
1.602
7
7
60
GTP
T. Blomqvist / C. Braun
Acura Meyer Shank Racing w/Curb Agajanian
Acura ARX-06
10.215
0.344
8
8
6
GTP
L. Vanthoor / K. Estre
Porsche Penske Motorsport
Porsche 963
10.735
0.52
9
9
24
GTP
S. van der Linde / D. Vanthoor
BMW M Team WRT
BMW M Hybrid V8
11.418
0.683
10
10
23
GTP
R. Gunn / R. De Angelis
ASTON MARTIN THOR Team
Aston Martin Valkyrie
12.558
1.14
11
11
5
GTP
T. van der Helm / L. Heinrich
JDC-Miller MotorSports
Porsche 963
2 Laps
2 Laps
12
1
2
GTD Pro
A. Garcia / A. Sims
Corvette Racing by Pratt Miller Motorsports
Chevrolet Corvette Z06
3 Laps
1 Lap
13
2
9
GTD Pro
A. Caldarelli / S. Mitchell
Pfaff Motorsports
Lamborghini Temerario
3 Laps
1.935
14
3
65
GTD Pro
C. Mies / F. Vervisch
Ford Racing
Ford Mustang GT3
3 Laps
1.897
15
4
1
GTD Pro
N. Verhagen / C. De Phillippi
Paul Miller Racing
BMW M4 GT3 EVO
3 Laps
1.329
16
5
64
GTD Pro
B. Barker / D. Olsen
Ford Racing
Ford Mustang GT3
3 Laps
0.769
17
6
14
GTD Pro
J. Hawksworth / B. Barnicoat
Vasser Sullivan Racing
Lexus RC F GT3
3 Laps
9.917
18
7
4
GTD Pro
T. Milner / N. Catsburg
Corvette Racing by Pratt Miller Motorsports
Chevrolet Corvette Z06
3 Laps
0.093
19
8
59
GTD Pro
M. Esterson / N. Johnson
RLL Team McLaren
McLaren 720S GT3
3 Laps
3.46
20
9
77
GTD Pro
N. Tandy / H. King
AO Racing
Porsche 911 GT3 R
4 Laps
1 Lap
DNF
10
15
GTD Pro
A. Telitz / C. Mostert
Vasser Sullivan Racing
Lexus RC F GT3