Mitchell, a 22-year-old from Forfar, looked on as team-mate Rob Collard, who had powered through from 13th in the ultra-competitive gold class to lie sixth, was pitched into the gravel.
The incident came just 37 minutes into the three-hour race and proved to be a massive set-back to the team’s chances.
Collard had been forced to start the race from last place on the 52-car grid after the Lamborghini suffered mechanical problems during qualifying.
“Qualifying was tricky for us,” Mitchell admitted following the race.
“We had a problem with the car which meant we couldn’t take part in quali three and resulted in us starting from the back of the grid.
"But Rob delivered a fantastic first stint in the race, moving up from 52nd to 34th overall at one stage.”
Collard’s drive, though, was then unceremoniously terminated as he was forced off the track.
Braking downhill as he entered the tight left-hander at Ravazza, impact from a chasing Mercedes, which subsequently received a drive-through penalty for its actions, spun Collard deep into the gravel.
“That split second essentially wrecked our race,” Mitchell said afterwards.
“After that it was a case of damage limitation.”
The marshals extracated the stricken Lamborghini from the gravel trap and Collard managed to get the car back to the pits for attention from the team.
But after that delay, plus additional necessary repair work carried out by the Barwell crew, by the time Mitchell’s team-mate Alex MacDowall rejoined the race for the second stint, the number 77 car had dropped eight laps and out of contention on the day.
Mitchell then took over the car for the final 60-minute stint and immediately set a number of fastest laps.
He set his quickest, 1min 41.443secs, on lap 75 of the 86 the car completed.
“It’s frustrating because we knew we had a quick car this weekend,” the Angus driver said.
“But it was important we got the car back on-track, and to battle back to finish ninth in class and 40th overall means we have scored a couple of championship points.
"They could be crucial at the end of the season.
“I felt sorry for Rob because he was putting together a terrific first stint,” Mitchell, who won the 2020 British GT title with the veteran BTCC racer, continued.
“We were confident of at least a top five finish today, but the early impact put an end to that.
“The Barwell guys did a fantastic job getting the car back on-track, and our pitstops were quick and seamless.
"I know we’ll be right back on the pace at the next round at Paul Ricard in June.”
Before that, Mitchell returns to action for the opening round of the British GT Championship on Easter Monday at Oulton Park.