"He (Piastri) is now going into his fourth year. Lando has a lot more grand prix than he does so if you look at the development of Lando over that time, Oscar's on a similar trajectory," Brown ahead of McLaren testing in Bahrain.
"So he's in a good place, physically very fit, excited, ready to go."
Piastri, who debuted with McLaren in Bahrain in 2023, would become Australia's first champion since Alan Jones in 1980.
While Piastri took his first win in his second season, Norris had to wait until his sixth. Both won seven times last year with Piastri 34 points ahead after his seventh win, at the Dutch GP, the 15th race of 24.
But Norris edged ahead after winning the 20th, in Mexico, and held on to win the title by two points from Max Verstappen with Piastri 13 points adrift in third.
Brown said he had spoken a lot with the Australian over the European winter break and expected the 24-year-old to pick up where he left off.
He said the discussion had been all about creating the best environment for him and what McLaren needed to do to support him.
Brown said Piastri had spent time in the simulator and, in response to a question about lingering sentiment in Australia that McLaren favoured Norris, "he knows he's getting a fair shake at it".
"You win some, you lose some. Things fall your way, things don't fall your way," added the chief executive.
The world champions McLaren unveiled the livery for their 2026 challenge on Monday, with the distinctive papaya colour staying put
"I'm excited. It is pretty special to look at. Excited to get behind the wheel," said Norris on a livestream
Piastri added about the new car: "Hopefully it is as successful as the last couple."
Brown reiterated that both drivers remained free to race and said decisions would be taken strategically as and when they arose.
"We feel like we'll be competitive. The top four teams all seem very competitive. Very early days but indications that we will be strong," he added.
Mercedes' George Russell is the current pre-season favourite after an initial shakedown test in Barcelona last month.
With DPA
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