Robert Lewandowski became the first player in Bundesliga history to score in eight successive away games and Thomas Muller scored twice as leaders Bayern Munich cruised to a 4-0 win over Schalke.

Second-place RB Leipzig suffered a shock loss to Mainz 05 on Saturday and Bayern took full advantage at the Veltins-Arena on Sunday, moving seven points clear at the top.

Schalke are bottom of the table with one win all season but they more than matched the European champions before Muller's 33rd-minute breakthrough.

Muller doubled his tally late on after Lewandowski had scored his latest record-breaking goal early in the second half, before David Alaba added further gloss at the death.

The division's leading scorer Lewandowski glanced over the crossbar from close range early on before a better chance came and went for Mark Uth, who headed straight at Manuel Neuer from five yards out.

Ralf Fahrmann was called into action with a fine double save to keep out Lewandowski's free-kick and Serge Gnabry's follow-up attempt. 

Gnabry went close again when glancing the side-netting with a header he should have put away, but Bayern were in front seven minutes later through Muller's powerful header. 

The attacking midfielder met Joshua Kimmich's back-post delivery and made no mistake in beating Fahrmann for his eighth league goal of the campaign. 

Gnabry thought he had added a quickfire second after Leroy Sane's initial effort was parried, only for the offside flag to go up against the former Schalke winger.

But the Bavarian giants did double their advantage early in the second period as Lewandowski controlled Kimmich's long ball, held off two defenders and slotted under Fahrmann.

It is the 11th successive Bundesliga game in which Lewandowski has scored against Schalke and he nearly added another, dragging wide from 18 yards 20 minutes from time.

Schalke are now without a win against Bayern in 21 league matches and badly faded in the closing stages, with Muller heading in from another Kimmich delivery and Alaba adding a fourth with a 30-yard drive that squirmed under Fahrmann.

Bayern Munich's shock DFB-Pokal loss to Holstein Kiel left Hansi Flick "very disappointed" but the head coach insisted the German and European champions must move on.

DFB-Pokal holders Bayern sensationally crashed out in the second round on Wednesday, stunned 6-5 on penalties following a 2-2 draw against second-tier Kiel after extra time.

A 95th-minute equaliser thwarted Bayern, who were on the brink of the last 16 thanks to Leroy Sane's sublime free-kick at Holstein-Stadion, where Serge Gnabry's opener had been cancelled out by Fin Bartels.

After Bayern substitute Marc Roca was denied by Ioannis Gelios, Bartels stepped up to complete the remarkable upset – the Bundesliga and Champions League holders beaten in a penalty shoot-out against a lower-tier side in the DFB-Pokal for only the second time after 2000.

"It's a shock of course. We're very disappointed, we wanted to defend the treble. Taken altogether it was down to details, the team showed great spirit," Flick said.

"We were dominant, which was our aim. It's very annoying that we conceded the equaliser in the last second. We must congratulate Kiel, they made it a real cup fight, they were completely committed. We must put it behind us and improve.

"We must be more compact at the back. We must apply more pressure and be more solid when it comes to balls over the top.

"It's surprising, that's what the cup is like. Kiel defended well, their keeper turned in an outstanding performance. It just happens in penalty shoot-outs, I don't blame Roca."

For the first time in more than 12 years, Bayern were forced into extra time against a lower-tier team in the DFB-Pokal after Kiel captain Hauke Wahl struck at the death.

Bayern star Thomas Muller added: "At the end of the day we lost against the underdogs from Kiel. It may sound silly after such a defeat but lady luck wasn't really on our side today.

"We had a pretty good feeling in the first half and played decently. We had good chances, we combined well, we enjoyed more of the ball. Kiel gave it their all. It was certainly a good performance from their point of view.

"It wasn't an upset that was looming from the off. We made mistakes when it came to the details and Kiel were pretty clinical, as they were in the shoot-out."