A unique selling point of Bayern Munich has a glaring flaw

Although Bayern Munich are the only club in Europe’s top five leagues still unbeaten, they are more vulnerable at this early stage of the season than they were last season.

Last season, Bayern Munich made history. Their 16 consecutive wins gave them the best start to a season in the history of Europe's top five leagues, breaking an AC Milan record that had stood for more than 30 years. The Italians had opened the 1992/93 season with 13 straight wins. Bayern did not drop their first points until 8 November, when they drew 2-2 with Union Berlin in the Bundesliga.

Bayern could not match that run early this season. Schalke 04 held them to a 0-0 draw in the Bundesliga in their fourth competitive match. After 13 matches, Bayern have dropped points on four occasions, also drawing with FC Augsburg, Viking Stavanger and Arsenal.

Across Europe's top five leagues, though, Bayern stand alone: they are the only side unbeaten in all competitions this season. The leaders of the other major leagues, Barcelona, Manchester City, Paris Saint-Germain and Inter Milan, have all lost at least twice.

Bayern's prolific attack has helped keep that unbeaten run intact. They have scored 47 goals already, an average of 3.6 per game, exactly the same as at this stage last season. Their two superstars have led the way: Michael Olise has a remarkable 19 goal contributions after 13 games, while world footballer of the year Harry Kane has 17. Bayern are somewhat reliant on the pair.

At the back, there is at least minor cause for concern. Bayern have conceded 14 goals, an average of more than one per game, and kept just three clean sheets in 13 competitive matches. They had twice as many after the same number of games last season. They have now conceded in six straight competitive matches, including at home to second-division side 1. FC Magdeburg in the DFB Cup.

Could a lack of familiarity playing together explain it? Bayern currently have no clearly preferred back four. Min-Jae Kim and Jonathan Tah are competing for the place alongside the established Dayot Upamecano. On the flanks, Josip Stanisic, Konrad Laimer, Nathaniel Brown and Alphonso Davies have had a similar number of opportunities, with no clear pecking order. Personnel shortages have also forced Laimer, Brown and Davies into more attacking roles.

On Saturday, Bayern face their toughest domestic rivals, Borussia Dortmund, in the Bundesliga's marquee fixture. They then travel to Atletico Madrid in the Champions League on Tuesday, with their unbeaten run facing two major tests in the coming days.