Mercedes chief race engineer Andrew Shovlin has said the team must keep developing the W11 to protect from the threat of a "not far off" Red Bull.
Mercedes was defeated for the first time in 2020 when Max Verstappen crossed the line to take victory in the 70th Anniversary Grand Prix.
Lewis Hamilton and Valtteri Bottas finished second and third, but a run of four consecutive podiums for Verstappen has caused concern for Mercedes, concerns which grew as the Dutchman leapfrogged Bottas into second place in the drivers' standings.
Shovlin said: "We've seen Red Bull, they’re not that far off us in races even when we’re looking at our best.
"So I think, to be honest, if we don’t make progress, we’ll be in trouble there as well. That’s where this urgency to get a bit of a grip on it comes from."
The mix of running tyres one step softer than in the British Grand Prix one week earlier and the considerably warmer conditions appeared to hinder Mercedes more than any other team on the grid.
Both drivers reported blistering early into each stint, and the majority of the race was spent conserving tyre life as opposed to battling Verstappen for victory.
Back onto a more favourable, harder tyre compound for the Spanish Grand Prix this coming weekend, Shovlin hopes the team can learn from its Silverstone struggles to cope with the even warmer conditions in Barcelona.
He added: "It’s not to say that right now we’ve learned because I think this is not a straightforward problem, this wasn’t something last year’s car suffered from.
"And this year’s car is by a large an evolution of last year’s car. There are not any areas where we changed philosophy, we’ve just been pushing down the same paths of development. Right now we don’t understand what the problem is.
"We didn’t really long-run here so it may have been something that was lurking in there all weekend, and it may have been something that we actually just dodged last weekend with the early safety car and being on the very hardest tyre for most of the race.
"But what we have got is a load of data. We got data from two different track conditions here, different compounds. There’s a lot that we can go off and try and pick through."
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