Lewis Hamilton has labelled Friday at the Japanese Grand Prix as "very challenging" as he could only manage 14th in practice.
The seven-time World Champion entered the weekend off the back of his podium result in Singapore, but Mercedes appeared well behind the Ferraris and Lando Norris with every driver well down on Max Verstappen's pace.
Hamilton struggled to get up to speed on the first day of running at Suzuka, highlighting a lack of confidence in the W14.
"It was a very challenging day for us out there," he said. "I had a lack of confidence in the car and that contributed to our struggles.
"It was difficult to find the right balance and we didn't manage to get on top of it by the end of FP2.
"The tyres were overheating and that left us quite far off the top of the timing sheets."
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Work to do
Hamilton is a four-time race winner around the Suzuka Circuit, however it is Red Bull that appears to be strongest after the opening day of running.
While his pace on Friday was lacklustre, Hamilton is confident that both he and Mercedes can turn their form around ahead of qualifying.
“We know we've got a lot of work to do tonight to pick up the performance,” he said. “I do believe we can make improvements though.
“We have had similar Friday's this season and come back stronger on Saturday. We will see tomorrow if we have done so again.
“We will be putting in the effort this evening to give us every chance of getting ourselves higher up the order.”