Lando Norris says his new teammate is a tougher challenge than the ousted Daniel Ricciardo.
The Woking based team decided to slip out of its contract with Australian Ricciardo at the end of last year, replacing him with his much-younger rookie countryman Oscar Piastri.
"He's doing really well, honestly," Norris is quoted by the Dutch source Formule 1. "He handles pressure very well, I think that's one of his strengths.
"He's calm, controlled and quick, so he's got a lot of what you need. He pushes me more compared to the competition I've had in recent years, which is also a good thing for us as a team."
Ricciardo, 33, is now a part-time ambassador and test driver for Red Bull Racing.
Boss Christian Horner thinks the 8-time team race winner "picked up some habits" during his years at McLaren - including getting so thin that Red Bull has had to "feed him up".
"It was clear when he came back that he had picked up some habits," he said. "We didn't recognise him as the Daniel that that had left us two or three years earlier."
For his part, Ricciardo says he has used his racing sabbatical so far to figure out what went wrong at McLaren.
"It's only been a few months," he told Speed Week, "but I already know what I want to do differently when I'm back on the grid next year.
"That's cool, because I wouldn't know if I was sitting in the car again this year."
Some believe Ricciardo is aiming to convince Red Bull to reunite him as Max Verstappen's teammate.
"I know where I want to be and that I thrive when the stakes are higher in a top team," he said. "I know it will probably be difficult to achieve that, but that's my goal."
