Having secured a third straight win of 2016 in China, Rosberg has amassed a perfect 75 points from the opening three races of the year - giving him a 36-point advantage over Hamilton. The Briton came from behind to beat Rosberg to the title in 2014, but the biggest deficit he ever faced was 25 points.
Asked if he was feeling unbeatable given such momentum, Rosberg replied: "Quite the contrary. My team mate is Lewis Hamilton, and he has been the benchmark for the last two years.
"The points gap is like nothing, if you consider all the points still up for grabs this year. It's a couple of races' difference.
"It will always be a tough battle against him. He's as focused and motivated as ever; he will never give up."
Rosberg also played down what is his best ever start to a Grand Prix season, adding: "It's too early to make any summaries. It's three races now and they've gone really well for me, but it's the longest season in F1 history with 21 races so that's 18 to go.
"It would not make sense to make any premature conclusions. Of course I'm happy with the way it's gone and I'm feeling good and the car's there, but I don't want to say more than that.
"I just take it race by race; I don't think beyond that."