After a three-match winless run, Carlo Ancelotti's methods are already being questioned.
The new Bayern coach was praised at the start of the season for his relaxed approach, after Guardiola's more rigid, detail-driven style. Now, the feeling is that players may be losing their drive and determination under Ancelotti.
Club boss Karl-Heinz Rummenigge felt obliged to slam the team's "unacceptable" performance in a 2-2 draw with 10-man Eintracht Frankfurt in the Bundesliga on Saturday. The media quickly suggested that some of Guardiola's discipline might be in order.
Bayern, which will be without Franck Ribery when it hosts PSV Eindhoven on Wednesday, has won 13 consecutive home matches — a Champions league record. The German side has three points, three less than group leader Atletico Madrid, which plays at Rostov.
GROUP A
Given how poorly Paris Saint-Germain's midfield played in the unimpressive 2-1 win against bottom-side Nancy in the French league on Saturday, coach Unai Emery will be desperate to have the experienced Thiago Motta back for the home game against Basel.
But Motta is struggling to shake off a muscle injury, meaning that PSG could be missing his snappy tackling, tactical discipline and astute passing against Basel - which has been consistently strong in midfield in recent years.
Arsenal, which leads the group with the same four points as PSG, hosts last-placed ludogorets Razgrad of Bulgaria.
GROUP B
UEFA says Napoli has a chance to become the first team in Champions league history to advance from its group after just three matches — if Napoli beats visiting Besiktas, and Dynamo Kiev draws with Benfica.
But, Napoli has lost consecutive Serie A matches for the first time under coach Maurizio Sarri and has to overcome a lengthy injury layoff for Arkadiusz Milik.