McLaren boss, Andreas Seidl admits the Woking team is in a "race against" time to get upgraded parts to Bahrain and thereby salvage the team's test.
Other than Daniel Ricciardo going down with a mystery illness, the team has been plagued by a brake issue over both days of testing.
As it awaits upgraded parts to be sent to Bahrain from its Woking HQ the team is limited to runs not exceeding ten laps at a time.
"After the good test we had in Barcelona, the first one-and-a-half days here definitely did not go to plan," Seidl told reporters.
"We have unexpectedly an issue with the front axle, with the brake, which we have to solve," he revealed. "So it' a race against time at the moment in order to get upgraded parts.
"We will make steps with modifications that we could do here in the track, which still allow us to work on the car, working on the understanding of the car as well," he added. "We could run some small upgrades on the car as well, in order to extract more performance from the package.
"I'm still optimistic that despite the running time we lost and the limited laps we can do that," he insisted, aware that the first race is just days away, "in the end, we can leave the track here well prepared for the first race weekend."
Check out our Friday gallery from Bahrain, here.