Lewis Hamilton's rivals will have to pounce on any periods of "inconsistency" from the reigning champ if they want to beat him; that's according to Nico Rosberg.
Hamilton has won three of the last four Drivers' Championship and heads into this season as the firm favourite to add a fifth crown to his growing list.
Rosberg, though, proved in 2016 that the Brit is beatable, one just needs to put in a "perfect season" to do so.
"The weakness Lewis has is a bit of inconsistency. He has these periods when he is just not on it," he told Sky Sports.
"If you are able to pounce in those periods and really make the most of it, you can keep him down for a while longer.
"You have to make the most of it, absolutely, and Sebastian [Vettel] did that pretty well last year.
"When Lewis has his good weekends he is almost unbeatable, he is unbelievably fast and maybe the best guy out there.
"The only way to beat Lewis is to be 100 per cent with everything, do the perfect season. Otherwise there is no chance."
— Lewis Hamilton (@LewisHamilton) March 18, 2018
The German, confirmed as a part-time Sky Sports commentator for the 2018 season, hopes that this season his replacement at Mercedes, Valtteri Bottas, will raise his game while the Ferrari and Red Bull drivers also get involved in the fight at the front.
"I hope that Valtteri can be even closer to [Lewis] this year, because last year he showed some really big flashes of brilliance but it just lacked in consistency," Rosberg added.
"I think he can do it, I think he can really ramp it up even further and get very, very close. That is what we want to see, we want to see a good internal battle there.
"Then Sebastian has to be the next one as a big challenger for Lewis. For Kimi, looking at last year, it will not be so easy but maybe he can find a little bit extra this year.
"Then the Red Bull guys it depends on their car. If the car is good, those two are some of the most exciting prospects and when they are up in front there is always action happening."