The striker made it seven goals in a week with a double on Saturday, while Kingsley Coman also found the back of the net after scoring his first goal for the club last weekend.
Robert Lewandowski reached a century of Bundesliga goals to help Bayern Munich secure its best start to a league season by comfortably beating Mainz 3-0 at the Coface Arena.
In his 168th league appearance, the Poland international picked up where he left off following his record-breaking five-goal haul in the 5-1 thrashing of Wolfsburg on Tuesday by netting a second-half brace.
Thomas Muller missed a first-half penalty before Lewandowski broke the deadlock and reached his milestone - he is the fastest non-German player to reach 100 league goals - after 51 minutes when he nodded in a perfect cross from Juventus loanee Kingsley Coman.