BERNEBayern Munich’s Champions League visit to Basel on Wednesday has all the ingredients for an upset, with the Bavarians in the middle of a rocky patch.Bastian Schweinsteiger’s injury, Arjen Robben’s loss of form and a dull goalless draw at Bundesliga strugglers Freiburg on Saturday combine to make Bayern look vulnerable.Basel have already pulled off one shock this season by taking four points out of six from Manchester United in the group stages to qualify for the last 16 at the expense of the Premier League side.The Swiss league champions also have inside knowledge of their opponents as coach Heiko Vogel spent nine years working with Bayern’s youth scheme where he coached several members of the current team.In another twist Basel winger Xherdan Shaqiri will be keen to show his future club what he is capable of, having already been signed by Bayern for next season.Basel are unbeaten in 13 matches in all competitions, their last defeat coming at home to Benfica in the Champions League in early November when Vogel took over following the sudden departure of Thorsten Fink to Hamburg SV."It’s special that there is Swiss involvement in the last 16, the fact I started my training career with Bayern makes it even more interesting,” said Vogel.Basel, who also reached the group stages in 2002-03, could be rusty though as they have played only twice since the winter break.