PARIS (AP) With his appeasing smile and calm voice, it would be easy to miss Nico Rosberg's growing frustration after two seasons finishing second behind world champion Lewis Hamilton.
Behind his ever-courteous demeanor, and although he jokingly says ''I wasn't permanently frustrated'' last year, the 30-year-old German driver is consumed by a desire to finally outdo his more illustrious Mercedes teammate.
Mercedes has the dominant car, and this could lead to another title scrap between the childhood friends whose idyllic teenage years racing karts against each other have turned into heated bickering between elite drivers.
It is typical Rosberg to downplay the bitterness of the rivalry and then stoke it up - sometimes in the same sentence - as he did last week when pre-season testing had ended in the Spanish sunshine of Barcelona.
''I wasn't permanently frustrated,'' he said, before quickly adding. ''In my life I always like to compete against people who've beaten me recently, to come back and try and beat them because that just gives me more pleasure. That's what I'm looking forward to this year. It's a great challenge: Lewis is driving at an awesome level.''
Frustration got the better of Rosberg more often than Hamilton last year; none more so than last October at the United States Grand Prix in Austin, Texas.
After the race, in which Hamilton secured his third world title, a disconsolate Rosberg was sitting in a corner of the green room when Hamilton somewhat dismissively tossed him a cap to wear on the celebratory podium.
A stunned Rosberg threw it straight back and was then critical of the British driver afterward, saying he had been ''too aggressive'' during the race.
Rosberg's main problem, apart from controlling his emotions, was carrying his speed in qualifying into the race - where Hamilton's more steely edge ultimately made the difference.
However, as Hamilton continued to celebrate his second straight title in the closing weeks of the season, Rosberg issued a telling reminder by winning the last three races.
''I'm sure there will be a lot of success this season and I'm looking forward to winning a lot of races - hopefully,'' said Rosberg, whose cautious nature prevents him making outright predictions. ''We all start from zero. But of course what I have is the positive memories from the end of last year.''
Mercedes head of motorsport Toto Wolff predicts the battle could intensify due to tougher restrictions on team-to-driver radio communications.
''There is much less information and data being provided to the drivers during the races: on engine modes, on tires and strategies,'' Wolff said. ''The natural outcome of these regulation changes is that it will be again much more down to the drivers to take decisions. That means that the direct competition between the two is guaranteed and will be more intense.''
Rosberg must now make his mark on F1 as a winner, rather than a late bloomer who almost made it.
His tally of 14 GP wins is relatively low for a top driver. He did not win his first race until 2012, and lags way behind Hamilton's 43 wins and Ferrari's Sebastian Vettel, who has 42.
He will be 31 in June and only has a few years left at the top, and there are massively talented young drivers like 18-year-old Max Verstappen or 21-year-old Daniil Kvyat waiting to show what they can do in a superior car.
Whether he can dominate Hamilton over a whole season remains to be seen. What is not in doubt, however, is that he is in the right car to sustain a challenge without being sidetracked by mechanical issues.
Over the F1 testing, Mercedes logged a mind-boggling 1,294 laps of the 4.655-kilometer (2.9-mile) Spanish circuit; equivalent to nearly 20 Grand Prix distances.
Ferrari, led by the cunning driving of four-time F1 champion Vettel, is again expected to be the main challenger.
Mercedes hardly used any soft tires in testing on the tough and grainy Catalunya circuit, preferring to keep its rivals in the dark about its outright speed on prime rubber.
''It's the compromise,'' Rosberg said. ''You don't really want to show everybody else how fast you are.''