George Russell thinks his rookie Williams Formula 1 team-mate Nicholas Latifi is under-rated and will be tougher for him to beat than most expect.
Russell made his debut in F1 last year and was faster than his returning team-mate Robert Kubica in all 21 qualifying sessions, and finished ahead of the one-time grand prix winner 16 times when both made the chequered flag.
However, Russell warned against predictions he will have a similar advantage over Latifi.
"You're only as good as your last race so it's a fresh start," said Russell.
"I think Nicholas is definitely very under-rated He's incredibly prepared.
"And he's going to be a tough driver to beat, so he is going to keep me on my toes. I'll be pushing."
Although Latifi is embarking on his first F1 season, he has taken part in 11 free practice sessions so far for Williams and Force India (now Racing Point).
He has also tested for Renault and Force India, and conducted a private young driver test for Mercedes in an old car alongside Russell back in 2017.
"Nicholas is a great driver but you know he's probably the most prepared rookie F1 has had ever almost," added Russell.
"He's driven a Force India, he's driven a Williams, he's driven a Mercedes, he's driven a Renault. He's been testing for three or four years now in F1.
"On paper he's a rookie, but the reality is he's not, and he's definitely going to be tough to beat.
"I'm ready for the challenge and looking forward to that battle."
Russell said he knows he needs to lift his own game in his sophomore campaign if he is to keep up his career momentum.
"I've got some specific goals I want to improve with my driving with what I think will make me go faster," he said. "It's work in progress.
"I was a better driver in Abu Dhabi than I was in Melbourne [in 2019]. I'm sure I'll be a better driver in Melbourne than I was in Abu Dhabi, and it's constant evolution.
"But I need to reach the levels I think I can, and I think I am on the way."
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Russell was eager to play down Williams's potential despite an encouraging start to testing, and insisted it was too early to feel anything had been achieved yet.
"What we saw obviously looks like a massive success versus last year, and it is, but the fact that we have a car at winter testing is not something to exactly celebrate," he explained.
"It should be normal."
He added: "The car is much more driveable than it was last year, it gives me much more confidence.
"But ultimately it doesn't matter how it feels. It matters how fast it is and that we don't know yet."