McLaren kicked off its pre-season test in Bahrain with a troubled opening day, with brake issues hindering Lando Norris' running and mileage.
The Briton concluded his day with the sixth fastest lap but only 50 laps under his belt despite spending the entire day at the wheel of his team's MCL35.
Rising brake temperatures limited the Briton to short runs, and Norris insists there's no quick fix to the problem.
"I think on the whole not the day we really wanted," Norris said. "We just had problems with the brakes today, simple as that.
"The exact problem I’m not too sure, just temperatures and stuff.
"It didn’t allow us to do long runs at least. There’s things we’re trying to fix for the next few days, it’s not going to be an easy fix.
"We’ll see what we can do. Everyone’s working hard to come up with something."
Norris was on his own on Thursday as Daniel Ricciardo was feeling under the weather, but so far the Aussie is still scheduled to drive on Friday.
Norris is hopeful that a compromise fix will at least allow his teammate and himself to cover more ground in the coming days.
"We hope to figure out things tonight and over tonight and into tomorrow and so on," he added.
"We’ll come up with compromises and things in there to allow us to do more running, for sure. The guys are already working on that.
"I’m not too sure just yet, I was just driving the car as much as I could and getting to know everything else. There’s just a lot of work to do."
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