the seven-time champion retired for the second time, Mercedes signed on Lewis Hamilton, another former champ.
While Hamilton has been collecting points consistently, Rosberg has been the faster driver almost halfway into the season.
Rosberg has won two of the last three races and had three poles, while Hamilton is still winless and had two poles.
But Hamilton is ahead on points, 89 to 82, which leaves Rosberg 50 points behind the series' leader, three-time champion Sebastian Vettel of Red Bull.
"In the short term I just want to annoy Sebastian and Red Bull, race by race, by being ahead of them," Rosberg said on Thursday at the German Grand Prix. "That is the most important thing, to be ahead not just of them but other teams.
"It is a really nice time in my career, it is new - I have never had a car as quick as it is now - and we can go out there and qualify and fight for the position right at the front.
"The car is getting better and better (in races), so on Sundays I can keep my qualifying position. That is a nice feeling, (and) very motivating."
Mercedes has held five of the last six poles, but has struggled to sustain the challenge in a race.
"Trying to win more races is what I am focused on at the moment, and what the team is focused on."
Rosberg believes new tires supplied by Pirelli could have an impact on qualifying and Sunday's race.
"It will be interesting," Rosberg said. "Possibly it will mix things up, but it is also an opportunity for us to understand it better than other teams and make the most of it. We have to try and run them as much as possible in relevant circumstance to try and learn as much as we can.
"It is likely to shuffle things around a bit."
Pirelli, under heavy fire after five drivers punctured at last Sunday's British GP, including race leader Hamilton, decided to use Kevlar belt tires this weekend, rather than ones with steel belts used in England.
Hamilton said Mercedes was improving, noting it was second in the constructors' championship.
"I'm 43 points off Sebastian, we've a good car," Hamilton said. "The improvements we have made with regard to tire degradation have helped, and moving forward I really hope we can be more competitive. As for the title, I'm just trying to stay within shooting distance, to stay in the fight. That's all I'm focusing on at the moment.
"Nico has proven we can win with the car, so I'm sure a win will come."