Mario Gomez plundered four goals as Bayern Munich hammered Freiburg while champions Borussia Dortmund were stunned at home by Hertha Berlin.fresh from scoring a hat-trick prior to the international break, Gomez helped himself to four goals in Bayern's 7-0 mauling of Freiburg at the Allianz Arena.Germany striker Gomez scored after just eight minutes before Franck Ribery weighed in with a brace before half-time either side of Rafinha hitting the post.Gomez added another on 52 minutes and completed his hat-trick three minutes later before converting from the penalty spot on 71 minutes.Substitute Nils Petersen wrapped up the scoring in the final minute to send Bayern back to the top of the table.Promoted Hertha enjoyed a surprise success on their travels after beating Bundesliga title holders Dortmund 2-1.Tunay Turun hit the post for Hertha after 16 minutes before the visitors took the lead five minutes after half-time through Raffael.Peter Niemeyer struck decisively for Hertha with nine minutes to go before Robert Lewandowski scored a consolation for Dortmund two minutes from time.Werder Bremen are level on points with Bayern after Claudio Pizarro scored a second-half brace in a 2-0 home success over Hamburg.Hannover suffered a first Bundesliga defeat of the season after crashing to a 3-0 reverse away to Stuttgart.Shinji Okazaki gave Stuttgart a ninth minute lead and goals inside the final 11 minutes from Zdravko Kuzmanovic and Serdar Tasci made the points safe.Netherlands international Ryan Babel scored a goal in each half as Hoffenheim romped to a 4-0 victory away to Mainz.Roberto Firmino provided Hoffenheim with a 16th minute lead before Babel converted from the penalty spot on the stroke of half-time after the former Liverpool attacker had been brought down.Babel notched his second of the game on 74 minutes before Nikolce Noveski's own goal five minutes from time compounded Mainz's misery.Borussia Monchengladbach continued their positive start to the season as Juan Arango's goal just before the hour mark clinched a 1-0 home triumph over winless Kaiserslautern. From / BBC .