Charles Leclerc has voiced his expectation that Mercedes will launch a comeback in form in the coming rounds.
The Brackley-based squad sprung out of the gates with the fastest car on the grid earlier this year, winning the opening six races.
However, it has since been caught by rival squads, with Ferrari and McLaren winning twice each at the last six rounds.
It has set up the prospect of a tense run to the end of the year, which was raised even further after Mercedes boss Toto Wolff declared the team has no money to continue the constant development of the car.
However, Leclerc is not convinced.
“I don’t know what they are preparing,” he told media including RacingNews365. “I don’t know what their plans are.
“I’m pretty sure they are not here just relaxing and watching races and enjoying the process.
“I’m pretty sure there’s a lot of hard work going on behind [the scenes], whether the budget is going for next year’s car or whether it’s coming later on this year.
“I don’t know, and only time will tell.”
A large portion of Mercedes’ success has been enjoyed by Kimi Antonelli, who currently holds a 59-point lead in the drivers’ standings.
With the Italian’s rivals chasing to close the gap, Leclerc insisted Mercedes’ early-season form showcases that it can’t be counted out of the equation.
“But I wouldn’t underestimate them, seeing how competitive they are since the beginning of the year,” he added.