Carlos Sainz says Ferrari got "something really wrong" at the French GP while Charles Leclerc bemoaned one of his "most difficult races" as the famous F1 team hit their first major stumbling block of an improved season.
Ferrari slumped from a super Saturday to a miserable Sunday at Paul Ricard as their drivers - who qualified fifth and seventh but were then both plagued by chronic race-day tyre problems - finished outside the top-10.
It was a harsh reality check for the Scuderia, who, after back-to-back pole positions in Monaco and Baku and a combined 36 points, were handed their first point-less weekend of the season while also losing their grip on third place in the Constructors' Championship as McLaren capitalised.
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"It's quite clear, quite evident that today we must have got something really wrong to be so far off the pace," admitted Sainz to Sky F1.
Leclerc added: "It's been one of the most difficult races of my time in Formula 1."
The issue for Ferrari was not one-lap pace, as evidenced by their qualifying and the start of their stints on Sunday. But while other drivers were able to maintain and pick up speed on old tyres, Sainz and Leclerc struggled massively with degradation and couldn't keep up with their midfield rivals.
"Cars that yesterday we were three tenths quicker than like the McLarens, today they were, towards the end of the race, two seconds faster per lap," said Sainz. "So it's clear that we have a limitation with tyres.
"It's something we will need to analyse and get better through the season. It's something I felt immediately when I got in the car in Bahrain, that something was not quite right there.
"It's time to get our head down and work around it because it's clearly limiting us on race day."
Leclerc was uncharacteristically off the pace compared to Sainz all weekend, and he finished five places behind his new team-mate in 16th in the race after pitting for a second time in a bid to find speed.
"I think both of the cars have been struggling massively," he stated. "We had five-six laps on the tyres where we were quite good and competitive, and even though we were trying to take care of the tyres, they were degrading so much.
"On my side we tried a second stop towards the end. We knew that we would be out of the points anyway and we just went for another stop and then it was quite tricky with blue flags.
"A very bad race for us."
Sky F1's Karun Chandhok commented on Ferrari: "I think they need to tune out some of pace for some longevity in terms of the race. Clearly they can't carry on this way.
"You can't have a car that's qualifying fifth and then finishing outside the points."
Ferrari are now 16 points behind McLaren in the standings and will hope to regroup for the Austria double header, on another fast circuit that may well not suit their car.
"It's hard to accept, but we will learn from it, determined to move forward," said team boss Mattia Binotto on the French GP. "Living through the experience of a race like this, can make you a stronger team."