Messi, who has banged in eight goals in his last three games, has 34 goals this term, with 25 in La Liga.
Rooney, who has 33 in total for Manchester United this season, leads the Golden Boot race by one with 26 Premier League goals.
World Footballer of the Year Messi said: "It would be wonderful to win the Golden Boot. I look at the list and it is sensational to see I have scored more goals than Didier Drogba.
"But to be just one goal behind Rooney is also enormous. Rooney is a big striker and what he is doing is developing into a phenomenal season."