Lewis Hamilton is expecting Ferrari and Red Bull to be genuine rivals to Mercedes when they arrive at the first race of the season in Australia later this month.
Mercedes' dominance of Formula One appears to be under greater threat this season than it has at any point during the last three years after Ferrari emerged as the stars of pre-season testing. The Italian team's fastest lap was over 0.6s quicker than the best effort by Mercedes and the SF70H's pace was also apparent over longer runs.
In recent years Mercedes has not shown its full hand until the teams reach the first race of the season in Melbourne, but Hamilton believes this year the competition at the front will be even closer.
"They [Ferrari] have been doing a fantastic job and I think there's more to come from them," he said. "I think their pace this week has been spectacular. I think Red Bull are still there, I don't know if they brought their upgrade package here this week but usually they bring it for the first race, so I expect us to be having a real serious battle with both these teams."
Testing is not always the best indicator of form, however, as heavier fuel loads and lower engine settings can be used to mask the real pace of a car on a qualifying simulation run. Ferrari's Sebastian Vettel even opted to lift the throttle coming out of the corner on one of his fastest laps, so as not to reveal his ultimate pace to the rest of the paddock on the timing screens.
"I don't know if there are mind games going on," Hamilton said. "Every year in testing the goal is not necessarily to go as quick as you can, it's to find out what you have in the car. And sometimes there have been potentially some teams sandbagging in the past, but I don't really see that as being a benefit to any team.
"Driving today, the time you saw was the time we could do. I didn't feel when I got out that I could have gone faster. But of course there are all sort of things that come into play to bring the time down, such as fuel loads, engine modes, those kind of things. The great thing is no one really knows. It looks very positive for Ferrari, that's for sure, and I don't think that's a bluff. I think that's true. They've done a great job."