Pep Guardiola and Leroy Sane should have been clear over the Manchester City's star's future while Bayern Munich were trying to arrange a transfer, according to ex-Bayern boss Ottmar Hitzfeld.
Sane's future at the Etihad Stadium has been the subject of much speculation since the end of last season following the winger's disappointing start to 2019.
The 23-year-old fell behind the likes of Raheem Sterling and Bernardo Silva in the pecking order in Guardiola's squad, ending the 2018-19 Premier League campaign with ten goals to his name from 31 appearances.
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Bayern have attempted to lure Sane back to Germany over the last few months, but Bavarian officials have previously baulked at City's €100 million ($111m, £91m) valuation of a prized asset.
The German champions were still hopeful of pushing a deal over the line before the September 2 European transfer deadline, until the former Schalke attacker suffered a serious injury in the Community Shield final.
Sane was stretchered off the pitch in the early stages of City's clash with Liverpool at Wembley on August 4, after sustaining anterior cruciate ligament damage.
Hitzfeld, who enjoyed two spells in charge at Bayern between 1998 and 2008, has blamed Sane for failing to clarify if he was open to a move before being ruled out of action for seven months.
"I did not find it correct from Sane that he did not announce himself, neither to Bayern nor to Manchester City," the 70-year-old told Blick.
Hitzfeld continued by insisting Sane's decision not to speak out on his future was "ridiculous", before also pointing the finger at Guardiola.
He took aim at the Spanish boss for starting Sane in the Community Shield despite his ongoing links to Bayern, adding: "I would not have done it, but if your club is about to sign such a big deal, you can not play your player in a rather insignificant game."
The Germany international is not expected to return to the pitch until next year and Hitzfeld now feels that Bayern should distance themselves from a player who may not return to full fitness again this season.
"A player with this injury is injured half a year and then takes half a year to get back," he said.
Bayern have managed to bring in Benjamin Pavard and Lucas Hernandez this summer, while also adding Ivan Perisic to their ranks on loan from Inter.
However, after Franck Ribery and Arjen Robben's departures at the end of last season, talismanic striker Robert Lewandowski has been among those to criticise the club for failing to strengthen the squad sufficiently ahead of the new Bundesliga season.