Lance Stroll fears Williams could struggle to hold its own in Melbourne this weekend with an FW41 which hasn't yet fulfilled the team's expectations.
The Grove-based outfit concluded 2017 in fifth position in the Constructors' standings behind F1's top three teams and Force India.
It's low-key performance in pre-season testing, and the undisputed progress registered by several of its mid-field rivals, underlines the hard work which remains ahead for the British squad which also fields this season the least experienced driver line-up in its history with Stroll and rookie Sergey Sirotkin.
"We definitely have to be concerned because it's not a secret that everyone looks pretty good this year, so it's going to be competitive," he said.
"But at the same time we just have to remain calm and wait to see what happens this weekend where we stand.
"The design of the new car is more daring, and it will take a little more time to get the most out of it," Stroll told the Canadian newspaper La Presse.
"The car is already better than last year's, but that's the same for everyone."
Williams' 2018 charger will likely remain a work in progress for the first few races of the season before the car enjoys a major upgrade package for the Spanish Grand Prix in mid-May.
However, missing out on points early on could prove costly in the long run, admits Claire Williams.
"We've got a huge development package for Barcelona – we'll have to wait and see where that puts us," said Williams' deputy team principal..
"I think that's what we all see – that you miss those points at the start of the season and you really regret that later.
"You kind of think 'well, it's a long year so if we don't do necessarily very well in the first few races it doesn't matter'. It actually is crucial to do well from the off."
Gallery: The beautiful wives and girlfriends of F1 drivers
Keep up to date with all the F1 news via Facebook and Twitter
