Mercedes' Trackside Engineering Director, Andrew Shovlin, says some failed set-up experiments were behind the Silver Arrows' mediocre pace during Friday practice for the Hungarian Grand Prix.
Drivers George Russell and Lewis Hamilton ended FP2 in eighth and 11th places respectively, having been fifth and seventh in FP1.
In both sessions, the Mercedes drivers were around one second off the fastest time, and Shovlin explained that the team had used Friday's running to try some set-ups that hadn't worked as hoped.
"We came in wanting to do some experiments with the car, and I think the ones that we did in FP2 have taken us backwards," Shovlin told Sky Sports F1.
"For the first session, we looked a bit stronger, the car was more together.
"There's a couple of things that I'm pretty certain we're going to be doing overnight, because it didn't look great."
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Rain throwing a spanner in the works
With heavy rain forecast for Saturday and cooler conditions predicted for Sunday's race, Shovlin added that Friday's running took on less significance than usual, with teams set to face a completely different set-up challenge in changeable conditions.
"In a way, [rain on Saturday] makes it not too bad that we've had a difficult FP2, because I think we'll be facing quite different conditions in FP3, and then the race looks like it's a lot cooler than today," he commented.
"It's not the end of the world, but it'd be nice to have a session where you can work with the car a bit, and this wasn't that.
"But there's plenty of data for us to go through. I think we know the first things we want to do, and then the wet is a different game altogether."
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