George Russell believes Daniel Ricciardo will have a "tricky" challenge on his hands at the outset at McLaren as he goes up against his "incredibly fast" teammate Lando Norris.
Ricciardo has moved to the Woking-based outfit after two years with Renault and with the ambition of carrying himself and his team back to the winner's circle.
But Russell believes that Norris' familiarity with McLaren coupled with his undeniable talent will pose a challenge to Ricciardo who has yet to fully settle in his new environment.
"I think Lando’s going to surprise a few people," the Williams driver told Sky Sports.
"He’s in his third season of Formula 1 now and third season with McLaren. He knows the team, knows the car inside out and all of the engineers.
"It’s going to be tricky for Daniel, coming into a new team and going against a guy like Lando who is incredibly fast and got the experience within that team.
"So yeah I think he will surprise a few people this year."
Assessing his own prospects after a productive three days of testing in Bahrain, Russell reiterated his fear of seeing Williams struggle in the lower tier of F1's midfield against a pair of rivals - Alfa Romeo and Haas - that will be powered by a much-improved Ferrari engine.
"We have got to be realistic," Russell said. "I think worst case scenario we will be in a similar position to last year, which was still a big step up from 2019. And obviously the Ferrari engine has taken a big step forward.
"Best case scenario I think we are fighting in the midfield. That’s what we are aiming for but it doesn’t mean that’s where we are going to be.
"Ultimately we have no idea how all the other teams have performed over the winter but I think the guys have done a good job and time will tell."