The major German newspaper Bild fears Rosberg is "too nice" to regain the upper hand now.
"Both are equally fast; equally good. But is Nico Rosberg too nice for the title?" wondered correspondent Helmut Uhl.
Indeed, Hamilton's previous teammate Button recalls that Hamilton reverted to "mind games" to gain the upper hand when they were paired at McLaren until 2012.
And with Mercedes now so dominant in 2014, "I am sure there will - if there aren't already - be mind games going on," Button said.
"There were a few things he played on me. It would work on some drivers, whereas others it just makes them stronger because they laugh it off.
"Nico is intelligent to know if Lewis is playing mind games or not, which in some ways could help Nico or harm him. He might just end up getting fed up with it."
At the end of the day, however, Button said form and confidence are the most important elements in a driver's armoury, and Hamilton is currently on top of his game.
"Lewis is full of confidence at the moment and he is a fierce competitor when he is like that, even when he is not having a good day," he told the Daily Mail.
But Button said that, given Mercedes' utter dominance this year, the battle between Hamilton and Rosberg will be an important factor in 2014 to keep interest levels high.
"The thing is, because they (Mercedes) are going to walk away with it - I know we are only five races in, but they have such a big lead - they're not going to favour just one driver," he said.
"They will let their drivers race because they need to keep the show going, and we need them to keep the show going and let both drivers race," Button added.