Lewis Hamilton is worried Mercedes could struggle in 2018 if it is unable to rectify "some really big problems" with its Formula One car.
Mercedes dominated F1 for three consecutive years following the sport's switch to the V6 turbo era in 2014, but an aerodynamic regulation overhaul last winter enabled rivals Ferrari to close the gap and challenge the Silver Arrows in both world championships.
The Brackley-based team has nine race wins to its name so far in 2017 -- compared to the 19 grands prix victories it claimed last season -- and has struggled to extract consistent performance levels from its complicated W08 at a number of races this year, especially at high-downforce tracks such as Monaco, Budapest and Singapore, though it was able to take an unlikely victory at the latter.
While Hamilton was able to extend his championship lead to 34 points over title rival Sebastian Vettel with second place at the Malaysian Grand Prix, Mercedes was left concerned by a "painful" lack of pace across the weekend. Despite enjoying a recent run of three consecutive victories, Hamilton fears his team could fall behind next season if it cannot solve the faults with its car.
"We've done an exceptional job with what we have," Hamilton said. "There are some really big problems which I can't really explain to you. But we really need to make sure we rectify them for next year's cars if we really want to fight both Ferrari and Red Bull when they step up their game.
"There is a lot of work for us to do -- but there's nothing we can do, it's the way the car is. People have been saying all year long that we've got the best car. It's a fact at some races that the car has turned out to be better but overall, globally, I think it's worked out that we haven't."
The upcoming Japanese Grand Prix at the power-hungry Suzuka Circuit should suit Mercedes' 2017 challenger and could go a long way in easing some of the reigning world champions' worries about being beaten to the title by Vettel's Ferrari. However, Hamilton is taking nothing for granted in the remaining five rounds.
"Suzuka is a much cooler circuit generally and the corners are a little bit different to what we experienced here, and we'll be on a different aero package as well so we should be better there," he explained. "But Mexico where it's full downforce will be a place of concern and we will probably struggle there, but there's not a massive amount of corners so maybe we will be OK.
"I think that's the only one -- this one and Mexico -- that has the high downforce and the others I'm hoping will be more similar to Spa and Silverstone. But it's difficult to say until we get there."