After defeat at home to Borussia Monchengladbach in the opening round of the 2011/12 Bundesliga, Bayern Munich won seven and drew one of their next eight matches, scoring 25 goals and, incredibly, conceding zero in the process. It left the Bavarian giants five points clear at the summit and seemingly cruising towards regaining the crown they relinquished to Borussia Dortmund in May. However, Jupp Heynckes’s side have lost three of their five outings thereafter, including their last two – 1-0 at home to Dortmund and 3-2 at Mainz. All of a sudden, they find themselves third, one point adrift of both the defending champions and Monchengladbach, with Werder Bremen three points off the pace and Schalke just a further point back in fifth. Oliver Kahn, who won eight Bundesliga titles with Bayern before his 2008 retirement, feels his former club have a real job on their hands to emerge with the trophy, especially given that they will continue to divide their focus between domestic and continental duties - at least until February. With a game to spare, Bayern have already booked their place in the knockout phase of the UEFA Champions League as Group A winners. Dortmund, by contrast, currently prop up Group F and run a severe risk of not just failing to reach the last 16, but also of missing out on a UEFA Europa League berth, for which they need to finish third in their pool. \"Borussia Dortmund have what it takes to be very serious contenders again this year,” Kahn, who won 86 caps for Germany between 1994 and 2006, told Bild. “It looked like Bayern were going to win the league rather easily only two weeks ago, but they have helped BVB back in the race. \"Dortmund have a huge advantage if they are going out of the European competitions and can solely focus on the Bundesliga. This could mean Bayern won\'t win the league as easily as many expected not too long ago.\" The top four will engage in battle in Round 15 on Saturday, with Bayern hosting Bremen and Monchengladbach entertaining Dortmund. Bayern have won 22 German top-flight titles, 13 more than nearest challengers Nuremberg. Schalke and Dortmund are next on the list on seven apiece. Bayern legends Click this Classic Players link to read about the superb careers of Bayern greats Franz Beckenbauer, Paul Breitner, Sepp Maier, Lothar Matthaus and Gerd Muller.