Williams chief technical officer Paddy Lowe did not entertain any questions about how reserve driver Robert Kubica fared against Lance Stroll and Sergey Sirotkin in pre-season testing.
The Pole was reportedly quicker at the Circuit de Catalunya than both Stroll and Sirotkin, prompting more questions to be asked as to why he was not given the 2018 drive ahead of Sirotkin, who made the move from a reserve role at Renault during the off-season.
But Lowe was particularly defensive when asked about Kubica's performance and how it matched up to the main driver line-up.
"I don't want to answer that question. I find that it's simply not worthy of an answer," Lowe said.
Lowe also insisted that Stroll will be a good barometer for Sirotkin's performance with a year of F1 experience under his belt.
"Lance is still very young but already on a completely different level to twelve months ago," said Lowe.
"It puts his position in a different context. It was almost too difficult for him to think 'My job is to be as strong as Felipe [Massa] last season."