Carlos Sainz's former Formula 3 boss Trevor Carlin believes Ferrari have underestimated him if they think he won't challenge Charles Leclerc.
Sebastian Vettel's confirmed departure at the end of 2020 started a chain reaction and Sainz was quickly named as his replacement.
Vetel and Leclerc were never far away from controversy in 2019 as the pair battled for No.1 status.
And Carlin belives that if they were bringing Sainz in to be Leclerc's No.2, then they may have made a mistake.
"Ferrari, if they thought they were hiring a number two, might have underestimated Carlos," he told Reuters.
"I hope they haven't done that.
"I know there's this story going around that Red Bull have got a number one, Mercedes have got a number one, Ferrari have got a number one. But I don't see that with Carlos.
"I think given the same kit and treatment and cars, he can run him close.
"I think Carlos is bloody good. Maybe Charles might edge him in qualifying but when it comes to the race, I think Carlos will be all over him. I think he's going to be fighting to earn his stripes there, he really is.
"I think the pressure actually will be on Charles' shoulders. "When Carlos really steps up he could be the surprise show there and make the tifosi (fans) very, very happy."
Sainz broke free from the Red Bull programme when he joined McLaren in 2019 and pumped in the strongest season of his career to finish P6 in the Drivers' Championship.
The Spaniard raced for Carlin back in 2012 in the British Formula 3 and Euro Series, and Trevor Carlin said 2019 was the Carlos that he knew back then.
"When you go through Toro Rosso and that whole movement around, you don't necessarily get the chance to develop fully," he said.
"To me, the driver we saw 12 months ago at McLaren when he became team-mates with Lando (Norris), that's the Carlos I remembered when he drove for us back in F3. Far more relaxed, far more comfortable in himself and far more confident.
"He's matured into the real deal. I was very, very happy for him."
Trevor Carlin said that Sainz's wet-weather racing was "exceptional" when he drove for the team, something he feels his father Carlos Sainz Sr, a rally legend, played a big part in developing.
"The one thing we noticed when he drove for us was in the wet Carlos was absolutely exceptional when he started out," he recalled.
"It was just ridiculous what he could do.
"That comes from driving dune buggies and dirt cars around the fields of Spain with his dad as a teacher. I think he would have been a damn good rally driver as well as a Formula 1 driver."