Sebastian Vettel says the updates implemented in France on Ferrari's SF90 haven't delivered the step forward that was expected.
The Scuderia introduced a revised front wing and brake duct for its 2019 contender as it seeks to improve the car's low-drag aero weakness
Vettel - who concluded Friday's FP2 session fourth with a 0.728s deficit to pacesetter Valtteri Bottas - was unimpressed when asked about the updates.
"Not so good, to be honest, a lot of work ahead of us," said the German.
"Yeah, [they] didn't bring what we were expecting, so we'll see what we can try and find overnight, to maybe be a bit better off tomorrow."
Charles Leclerc said an optimum package would be put together for Saturday using a selection of the best elements that were tested.
"Some parts were very good, some others a bit less, so tomorrow we'll put everything together and hopefully it will be a positive day for us," said the Monegasque.
Scuderia boss Mattia Binotto acknowledged the lack of progress achieved with some of the new parts but insisted the entire package would not be dismissed.
"I think we brought here some parts which were important for us to test to understand the direction of development," explained the Swiss.
"We tested a few parts, some of them will be kept on the car for the rest of the weekend so it is not an entire package that has been cancelled or not.
"A few parts will be kept and considered positive, and the ones that have been removed are considered part of our test plan but not intended to be raced for the weekend."
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