The Dons went joint-top thanks to a 4-0 mauling of Ross County on Saturday.
Everyone started writing off the Reds' title aspirations after Celtic reclaimed SPFL top slot from the Pittodrie club at the end of January.
But that suits Dons top scorer Rooney, who is happy to be underdog and keep the pressure on title favourites Celtic.
He said: "The view of everyone all over the UK is probably that it’s Celtic's league to lose.
"They have won it so many times and they have run away with it in the last number of years.
"There is obviously a pressure on them all the time whereas we are just developing as a squad.
"We just need to keep grinding out the wins and get as many points as we can.
"We are working hard each day to make progress and make sure that we did better than we did last year.
"That is always the aim."
Source: Daily Record