Charles Leclerc has confirmed Red Bull's fears by declaring Canadian Grand Prix practice as Ferrari's best Friday performance of the F1 2023 season.
Ferrari have disappointed so far this year, with Leclerc's third-place finish in Azerbaijan the team's only podium from the first seven races of 2023.
Having failed to win a race since last July's Austrian GP, Ferrari introduced a major upgrade package at the previous race in Spain - including a more conventional sidepod design - as the Scuderia attempt to return to regular victory contention.
Despite failing to deliver an immediate improvement in Barcelona, Ferrari looked competitive from the beginning of FP2 in Canada with Leclerc and Carlos Sainz trading fastest laps early on before finishing in the top five - ahead of the dominant Red Bulls of Max Verstappen and Sergio Perez.
At close of play on Friday, Red Bull advisor Helmut Marko admitted he was alarmed by the improved pace of Ferrari and Mercedes in Montreal and drew special attention to a long run by Leclerc.
"Leclerc's long run was very impressive," Marko told ServusTV.
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After FP2, Leclerc revealed the session ranks as one of Ferrari's best of 2023 - but with rain expected for qualifying, he has warned the team must start from scratch on Saturday.
He told Formula 1: "In terms of feeling it's been up there, yes.
"In terms of feeling, it's among the good Fridays for us.
"Really, really good feeling with the car so that's positive. Tomorrow will be a completely new day and, honestly, I don't think there's much that we can bring from today to tomorrow as it's going to rain probably.
"So it's going to be very interesting, but it's been a positive Friday."
Asked specifically about the SF23's pace over the long run on high fuel, he replied: "Again, really, really good. So that's positive, but it's only Friday so we need to wait and see but the feeling was good, pace looked really good.
"It's been a positive Friday. Now we just need to have a clean qualifying tomorrow in very tricky conditions and see what's possible on Sunday."
Leclerc added that Ferrari's improved performance from Barcelona to Montreal has come as a result of a greater understanding of the upgrade, with no major differences to the last race.
"We didn't do any significant change," he said. "We are obviously learning [about] this package more and more, so we are optimising it. It was a good day because everything we've done to the car went in the right direction, so that's good."