Craft-Bamboo's Mercedes-AMG GT3 looks set to miss qualifying after the team discovered an engine issue overnight.
The Hong Kong-based entry is one of the hot favourites for overall LIQUI MOLY Bathurst 12 Hour honours.
However, the team has become another squad to suffer a setback even before qualifying.
The #91 Mercedes was loaded onto a flatbed truck and taken into the city as cars cycled around for Practice 5.
There, it will undergo an engine change; there were just four hours until qualifying to make the change.
The team discovered the issue overnight, which it determined could potentially lead to a reliability problem in Sunday's race.
Team director Darryl O'Young confirmed to Supercars.com that the team didn't want to risk a failure.
"We saw irregularities in our data," he explained.
"We may miss qualifying, but we don't want to risk it for the race.
"We've made the decision to make an engine change, and we'll try to get out for qualifying.
"Our priority is having a reliable car for tomorrow's race."
The Craft-Bamboo squad has joined the list of teams that have already struck trouble in Bathurst.
The #91 Mercedes and #47 Audi did not take part in the all-in Practice 5 on Saturday morning.
The team on the #47 Audi is facing a race against time following a Friday crash for Theo Koundouris.
Koundouris crashed during Practice 3 at Reid Park, triggering a red flag.
The crash damage forced the Melbourne team to bring a spare Evo I-specification chassis to Bathurst.
Triple Eight was also forced to repair front-end damage to the #888 Mercedes-AMG.
Prince Jefri Ibrahim found the wall at Griffins Bend in the early stages of Practice 3.
The team repaired the car in time for Practice 4, with Broc Feeney setting the ninth quickest time.
Practice 5 was again topped by an Audi, this time by the #777 of Markus Winkelhock.