Former world champion Mika Hakkinen described the Russian Grand Prix as a the latest "tough lesson" for Charles Leclerc after Sochi represented a fourth failure to convert pole position into a victory for the Monegasque.
Leclerc has taken top honours on a Saturday six times in 2019 – more than any other driver on the grid.
However, only in Belgium and Italy has he taken to the top step of the podium, having suffered engine failure in Bahrain, lost out of Max Verstappen in Austria, before recent disappointments in Singapore and Russia.
Ferrari inadvertently undercut Leclerc with team-mate Sebastian Vettel in Singapore, while Vettel's refusal to follow a team plan in Sochi caused internal chaos before his retirement brought out a Virtual Safety Car to unwittingly hand the race to Mercedes.
Two-time drivers' champion Hakkinen is concerned that the current state of affairs between Vettel and Leclerc spells trouble for Ferrari.
Hakkinen wrote for Unibet: "After starting from pole position - his fourth pole in a row - Charles Leclerc had every right to expect a great result on Sunday, but it all went wrong when he agreed to give Sebastian a tow down the long straight to the first proper corner, Turn 2.
"In agreeing to give Sebastian the lead it opened up the opportunity for him to control the race, which he did perfectly.
"There is tension in Ferrari between the drivers, and Charles is learning some tough lessons. Including the fact that Sebastian did not win four World Championships by being a pushover.
"Compared to Mercedes, Ferrari does not yet have the perfect teamwork between the drivers, and they need to do that if they are going to win consistently. Fighting inside a team never works."
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