George Russell insists Ferrari and McLaren are currently all round stronger than Mercedes, but the Briton admits that could change down the road between now and the start of the 2022 season.
Russell clocked in fourth fastest at the end of Thursday's session, behind Ferrari pacesetter Charles Leclerc, AlphaTauri's Pierre Gasly and McLaren's Daniel Ricciardo.
The Briton's performance reflects Mercedes's P4 position in the pecking order after two days of running at the Circuit de Catalunya.
©Mercedes
"We’re seeing some interesting things out there," Russell said. "That’s what testing is for.
"Some teams are looking pretty fast, a red team [Ferrari] and an orange team [McLaren] in particular look very, very competitive.
"Let’s see what tomorrow brings and what we can do between this test and Bahrain."
Asked about Mercedes' performance relative to its top rivals, Russell said: "Certainly not ahead – pretty sure of that.
"They seem to have things well under control and they are on top of everything and they look very strong, low fuel and high fuel. And with the tyre management."
But the 24-year-old Mercedes charger also pointed out that comparisons are often futile as teams run different programmes over the course of the day.
"We all know we’re on different [run] programmes but we definitely know from the average of all the different runs we’re behind them at the moment," he said, referring to McLaren and Ferrari.
"Let’s wait and see. The championship is not won in Barcelona winter testing. It’s certainly been an intriguing two days."
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