Sebastian Vettel's commanding victory at Spa-Francorchamps proved just how strong the Ferrari package is, but Valtteri says that hasn't impacted the motivation and spirit within the team.
"In Spa, we definitely saw Ferrari were a little bit quicker than us on Sunday," Valtteri explained. "Sebastian kind of had control of the race and they had the upper hand there.
"We really need to improve our package to win this Championship. We are very motivated. Worried for me is the wrong word, we know the fact that it is going to be a big battle until the end of the year and we accept the situation that we need to improve the car in all areas.
"The working spirit is really good, we are not standing still that's for sure. The feeling is very good in the team.
"I think we have improved the whole package, we also had a new engine in Spa which was an improvement.
"During the summer, Ferrari made big gains with the Power Unit. Now they are the quickest car on the straights. It suggests they will be in front here as well."