Mercedes' consistent pace and incredible mileage in this week's Barcelona test should serve as a warning to rivals about its potential to keep dominating Formula 1, says Felipe Massa.
The Brackley-based team caused a surprise in the first test when it completed an incredible number of laps without major problems, setting itself up to hit the ground running in 2016.
And with other teams unable to match that performance early on, Massa thinks that there is a clear indication that F1 should be braced for more Mercedes success.
"Even without them doing so many runs like they did, I think it is already a big warning for the season - compared to what they did in the last two years and how they finished the season and the car they had,” he said.
“It is a warning situation: what they are doing at the track shows that they are going to be there, very very strong again.”
Key test coming up
Massa's final day of running with Williams this week on Thursday was blighted by an unspecified systems issue that limited his time on-track.
But he thinks a solution to the problem is easy to put in place, and that hopes are high the team can get through the mileage it needs to do next week.
“It was not really a great day,” he said. “We didn't do so many laps like we did yesterday and today we had some issues that took time to change in the car.
“I think the only positive thing that we did our aerodynamic testing in the morning is to try to analyse all the numbers around the car, and that actually was more or less the only thing we did.
“We did only a few laps but, sure, we lost massive time. It was not a very useful day, which can happen at the beginning.
"But I really hope we analyse everything we did and try to do long-distance next week."