Lewis Hamilton believes Mercedes needs to take a step forward overnight to find enough pace to challenge Red Bull in the Italian Grand Prix.
Sebastian Vettel topped the timesheets on the opening day of practice at Monza, 0.623 seconds clear of team-mate Mark Webber with Hamilton just under nine tenths off the pace.
While content with the handling of his Mercedes, Hamilton wants the team to work on the set-up ahead of tomorrow's running.
"Nothing special, but it was OK," said Hamilton of his Friday practice running.
"It has been quite a smooth day. We're not as fast as the Red Bulls, but we are still confident.
"The Red Bull is quick but generally the car feels good so I have to sit and try and understand [where to find the pace]
"I feel like I am on the limit everywhere and the car feels reasonably balanced.
"Maybe we are running too much wing? We'll see."
Hamilton downplayed his chances of gunning for pole position given the pace of the Red Bull.
But he did not rule out the competitive order changing on Saturday.
"Right now, it doesn't look massively strong for tomorrow," he said.
"But hopefully we can improve the pace. You don't know what fuel loads people are on so we will wait and see."
Team-mate Nico Rosberg admitted he is worried about the speed of the Red Bulls.
Like Hamilton, he is optimistic about the chances of Mercedes improving their car, but admitted it would be hard to beat Red Bull.
"I'm quite confident," he said. "The Red Bull time was a bit worrying, they are very quick again and it will be tough to beat them probably."