Bayern Munich boss Pep Guardiola says he is not overly concerned after his side suffered a 4-2 defeat at the hands of Borussia Dortmund in the German Super Cup.Dortmund took the lead early on after Bayern keeper Tom Starke was unable to keep out Marco Reus' diving header to take a 1-0 lead into the half-time break.Shortly after the start of the second-half, the Bavarians were level when Arjen Robben capitalised on a fantastic cross from Philipp Lahm. However, their joy was short-lived as a mix-up in defence ended with Daniel Van Buyten heading into his own net just minutes later.Die Borussen then extended their lead when Ilkay Gundogan stunningly curled his shot into the bottom corner from the edge of the area.Robben added his second of the game to reduce the deficit, again linking up with Lahm down the right-hand side, but it would mean little at the end.The game was decided as a contest in the 86th minute when Reus scored an easy tap in after some great dribbling by new-boy Pierre-Emerick Aubameyang on the counter-attack.The loss is Bayern's worst since their 5-2 reverse to the same opposition in the 2012 German Cup final, but Guardiola is confident his side will be much more fluid by the time the 2013/14 Bundesliga campaign kicks off on August 9."Overall, I am happy with the performance," the former Barcelona boss said. "We played well and what happened came down to individual situations."Even though we lost, I didn't get the feeling that Dortmund were better than us."We still have ten days to get ready for the Bundesliga restart and to correct our minor errors."