Toto Wolff has described Mercedes' performance level in Friday's opening free practice session for the French Grand Prix as "underwhelming".
After a difficult start to the season, Mercedes have been pushing to close in on front-runners Red Bull and Ferrari at recent events, claiming four podiums on the bounce.
The smooth nature of the Circuit Paul Ricard had also been tipped to help the team amid their ongoing battle with porpoising.
But the Silver Arrows started the weekend the best part of a second off the pace set by Charles Leclerc and Max Verstappen.
George Russell was the lead Mercedes driver in fourth, with Formula 2 and Formula E title winner Nyck de Vries – getting a 'young driver' run in Lewis Hamilton's car – half a second further back in ninth.
Mercedes simply "lacking pace" in FP1 at Paul Ricard
Reflecting on the session, Wolff pointed to struggles getting the Pirelli tyres in their "optimum grip window".
"It's not where we want to be," the Mercedes boss told Sky Sports F1 after FP1.
"We're trying lots of parts, but we're just lacking pace at the moment in the free practice session.
"It's early days, but the performance in FP1 was a bit underwhelming. We don't seem to extract enough out of it.
"We're going to do some [comparisons] and see what it gives in [FP2 in] the afternoon."
As for the upgrades Mercedes have brought to the track this weekend, Wolff said: "We have a few aerodynamic modifications on the floor, on the side edges – little things that should make it better."
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Wolff surprised by Hamilton sitting in the garage
Wolff went on to describe his surprise at Hamilton sitting at the back of the Mercedes garage at the start of the session.
It marked the first time Hamilton has given up his car in what is his 300th Grand Prix appearance to date.
"I was a bit confused!" Wolff said, when asked about Hamilton being on the sidelines.
"I came in [the garage] and he sat on my seat, and I thought, 'Why are you not in the car?' And then obviously I realised..."
Wolff also revealed the role the seven-time World Champion played from the garage.
"He was coaching Nyck," the Austrian went on to comment.
"He was helping him with the [telemetry] overlays and it was quite interesting to see."
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