Douglas Costa and Kingsley Coman were unable to make a meaningful impact in place of first-choice wingers Franck Ribery and Arjen Robben, while Thomas Muller again lacked sharpness in front of goal in the absence of suspended top scorer Robert Lewandowski.
Bayern laboured early on and it was not until after the half-hour mark that they looked like breaking through, David Alaba and Arturo Vidal denied by two goal-line clearances in quick succession from Leverkusen.
Coman also failed to convert from little more than six yards out, but the balance appeared to tilt in Bayern’s favour when Tin Jedvaj was shown a second yellow card for a reckless challenge on Muller in the 59th minute.
Ancelotti sent Robben, Xabi Alonso and Philipp Lahm on – the Dutchman making his 250th competitive appearance for the club – in a bid to improve his side’s creative prowess, but a goal that would have put them two wins from the title never came and they will need to pick themselves up ahead of the trip to the Santiago Bernabeu.
Carlo Ancelotti made five changes from the 2-1 Champions League defeat to Real Madrid on Wednesday to keep key players fresh for Tuesday’s return leg, but those who came in failed to impress and RB Leipzig now sit just eight points back after a 4-0 thumping of Freiburg earlier in the day.