Lewis Hamilton believes Red Bull holds an edge over Mercedes after Friday's opening day of running at the Belgian Grand Prix, admitting the Black Arrows outfit still "has work to do".
Mercedes led the field in FP1 from Max Verstappen, albeit by a small margin, but the Dutchman was in command in the afternoon session, edging Renault's Daniel Ricciardo and Hamilton, with Bottas clocking in only sixth.
There was only a 0.096s spread that separated the top three, leaving Hamilton convinced that Mercedes well be given a run for its money by Red Bull this weekend.
"It's very close out there between us," said the six-time world champion. "I think the Red Bulls are just a little bit quicker at the moment. But even Racing Point, I think it is right with us. And then also Daniel Ricardo is very close.
"So that makes it exciting. We've got some work to do, that's for sure, to try and dial in the car a bit more. But it doesn't feel bad at all."
Hamilton views the close competition as a logical consequence of the field tightening up as the season unfolds.
"I think the car is just from race to race, it's just different," he added. "Each race we go, some places we're ahead, some places we are behind.
"As I anticipated coming to this weekend, we're only into the seventh race, the field is going to get closer and closer as the whole of F1 develops.
"It's already showing this weekend as we seem to be so close with everyone. And we've got to understand why - whether they've taken a step or we've taken a step back?
"Or is it just the track layout or downforce level? Who knows? We'll work on that. But I'm excited for an interesting race, that is for sure."
Mercedes trackside engineering director Andrew Shovlin singled out the Mercedes W11's front end as an area that required attention.
"Both drivers have struggled a bit with the balance, mainly with a weak front end and we looked a bit slower than we normally do on a Friday even when the car seems to be working well," explained Shovlin.
"We've got a few areas that we are already looking into and hopefully we can make some progress for tomorrow.
"On the high fuel runs the midfield appears a bit closer than they did in previous races, so we can probably find a bit of time there.
"Looking at the forecast, there's a good chance of rain on Sunday, which would make this a very exciting race."
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