Robert Lewandowski humiliated his old club on Saturday as Bayern Munich obliterated Borussia Dortmund with a scintillating 5-0 win to reclaim their spot at the top of the Bundesliga.
Bayern began the day under immense pressure, having slipped two points behind Dortmund in the title race a week earlier.
They ended it on cloud nine, after a masterful first-half performance left Dortmund in the dust and put Bayern on course for a seventh successive league title.
The champions are now just a single point ahead of Dortmund in the title race, but the two teams were separated by a gargantuan gulf in quality at the Allianz Arena.
Mahmoud Dahoud struck the post early on for the visitors, but two quick goals from former Dortmund players put a dominant Bayern firmly in the driving seat.
Hummels landed the first blow on ten minutes, rising high at a corner to head in the opener for Bayern.
Lewandowski then pounced on a mistake by Dortmund centre-back Dan-Axel Zagadou to double the lead.
Having robbed Zagadou of possession, Lewandowski then looped the ball over goalkeeper Roman Buerki and scissor-kicked it into the open net.
Buerki kept a furious Bayern at bay for a short while, denying Lewandowski, Hummels and Thomas Mueller with a series of saves.
But the Dortmund keeper could do nothing to stop the Bavarians' third, a blistering strike from the edge of the area from Javi Martinez.
With their defence in disarray, Dortmund could only watch on as Serge Gnabry headed in Bayern's fourth just before half-time.
Lewandowski rubbed salt in the wound by netting his second goal just before full-time.
The win leaves the title race finely poised on paper, but with Dortmund in the doldrums and Bayern bouncing, Niko Kovac's side are now firm favourites to finish first.