Lewandowski's 24th-minute goal put Niko Kovac's side, which is set to sign Barcelona's Philippe Coutinho on loan, ahead on Saturday (AEST) but Hertha turned the game on its head in the space of two minutes.

Dodi Lukebakio's fortunate strike restored parity in the 36th minute before Marko Grujic capitalised on sloppy Bayern defending.

Grujic turned from Hertha's hero to villain just prior to the hour when his needless foul on Lewandowski was spotted by VAR, but although Bayern's striker tucked in the resulting penalty, the hosts could not carve out a winner.

Bayern wasted little time in flexing its muscles and the reigning champion hit the front when Lewandowski pounced on Serge Gnabry's cross.

Gnabry turned provider again two minutes later, but Corentin Tolisso was unable to beat Rune Jarstein and Bayern was swiftly made to pay for the miss.

Lukebakio tried his luck from range and was rewarded as his effort deflected off Vedad Ibisevic and beyond a flat-footed Manuel Neuer.

The turnaround was complete two minutes later, Grujic racing onto Ibisevic's throughball before coolly slotting under Neuer.

Jarstein came to Hertha's rescue again after the restart, diving in bravely at Kingsley Coman's feet before he pulled off a superb stop to deny Gnabry.

But Jarstein's good work was undone when Grujic ludicrously hauled down Lewandowski, who sent Hertha's goalkeeper the wrong way from 12 yards.

Lewandowski looked set to snatch the spoils in the final minute of stoppage-time but, under pressure from a defender, failed to direct his close-range header on target as Bayern had to settle for a point.

Kovac came under much scrutiny last season but his side ended 2018-2019 in sensational form, going unbeaten in its final 14 Bundesliga matches as it snatched the title ahead of Borussia Dortmund and then won the DFB-Pokal.

But, having already lost to Dortmund in the DFL-Supercup, Bayern knows that even the goals of Lewandowski and imminent arrival of Coutinho may not be enough to hold off Lucien Favre's side for a second season running.

Bayern travels to Schalke on 25 August (AEST) in what is David Wagner's first home game in charge of his new club, while Hertha hosts Wolfsburg.