Bayern Munich striker Thomas Muller has joked that he is 'being watched by the doping authorities' following his recent run of standout form for the club.

Muller was on the scoresheet twice as he helped to lead the German champions to a 5-1 win over Borussia Dortmund in Der Klassiker on Sunday, and the 26-year-old has since stated that the win should also send out a signal to the rest of the league.

"The guys from the doping authority are watching me," joked Muller after the game, according to Goal.com.

"Jerome [Boateng] and I exchanged glances and he put the ball into the empty space. You can't plan every action. You have to react quickly.

"We didn't practice long balls. But when there's room up the pitch, that's what you do in football. The way we won was a signal to our Bundesliga rivals."

Munich have now won eight games from eight this season and occupy top spot in the table.