London: Reigning Formula One champion Lewis Hamilton has said it is "game on" in the world championship battle, while his Mercedes team-mate Nico Rosberg is treating every race "like a cup final". Hamilton, 31, holds a nine-point lead over his German rival after Rosberg was victorious in the Belgium Grand Prix on Sunday. That ended a run of four straight wins for Hamilton, who had trailed by 43 points after four races. Formula 1 heads to Italy this weekend, with eight races remaining. "I'm really enjoying the battle out there right now," Rosberg was quoted as saying by the BBC on Wednesday. "We've got several cars in the mix now which is exciting for us and the fans. I'm taking every race like a cup final." Despite losing in Belgium, Hamilton had an encouraging weekend, finishing third inspite of starting on the back row because of a 60-place penalty. "It's game on for me now with the penalties out of the way and fresh engines ready to use. I can't wait to get back out there." The battle for the title is as tight as it has been since Hamilton and Rosberg were paired at team Mercedes in 2013, with the former looking for a hat-trick of world titles. Team Mercedes head Toto Wolff believes it will remain impossible to predict a winner until the end of the season. "My gut feeling is we will go long into the season before we see who comes out on top," Wolff said.