Borussia Dortmund slumped to its fourth defeat in five Bundesliga games Saturday with a 2-1 loss at Cologne, while league leader Bayern Munich routed helpless Werder Bremen 6-0.

Despite the return of key players from injury, Dortmund was unable to snap its five-game run without a win and the club sits two points off the relegation zone after eight games.

Kevin Vogt put Cologne ahead five minutes before the break, and though Ciro Immobile equalized three minutes after it, a mistake from goalkeeper Roman Weidenfeller gifted Simon Zoller the winner in the 74th.

Bayern captain Philipp Lahm and Mario Goetze both scored twice as Bayern warmed up for Tuesday's Champions League game at Roma with a comfortable win. Top striker Robert Lewandowski remained on the bench.

Elsewhere, Stuttgart fought from three goals down to draw 3-3 with Bayer Leverkusen, Borussia Moenchengladbach defeated Hannover 3-0 away, Wolfsburg won 2-1 at Freiburg, and Mainz beat Augsburg 2-1.

Schalke was hosting Hertha Berlin in the late game with new coach Roberto di Matteo in charge.

Ilkay Gundogan started in midfield for Dortmund after 14 months out with back problems. Henrikh Mkhitaryan and Marco Reus also started after recovering from injury.

Defensive problems cost Dortmund dearly.

Vogt beat Gundogan in a challenge for the ball, played a one-two with Marcel Risse and ran into the space left by Mats Hummels before beating Weidenfeller in a one-on-one. It was Cologne's first goal at home this season.

Reus set up Immobile's equalizer, but hopes of a comeback were dashed when Weidenfeller let Yuya Osako's harmless-looking cross through for the unmarked Zoller to claim the winner.

Bayern had no such problems.

Lahm hammered the ball home for his first goal of the season in the 20th, and Xabi Alonso scored his first Bundesliga goal seven minutes later, when he shot under the Bremen wall inside the left post. It was the Spaniard's 61st touch of the ball.

Alonso, who set a Bundesliga record with his 206 ball touches in the previous game against Cologne, had 21 touches in the first five minutes alone, two more than all the Bremen players together.

Thomas Mueller scored a penalty in the 43rd, and Goetze claimed his first with a fine finish inside the far post two minutes later.

With one eye on the trip to Roma, Pep Guardiola took Alonso and Arjen Robben off in the 61st, replacing them with Xherdan Shaqiri and Franck Ribery. Ribery was making his comeback from a left knee injury.

Lahm scored two goals in a Bundesliga game for the first time by claiming his second in the 79th, before Goetze scored again in the 86th.

Bremen became the first side not to have a single shot on goal in 6,495 Bundesliga games since records were kept in 1993/94.

In Stuttgart, Heung-min Son opened the scoring in the fourth minute, then intercepted Stuttgart 'keeper Thorsten Kirschbaum's attempted kick-out and replied with a wonderful strike to make it 2-0 five minutes later. The South Korean almost had a hat-trick a minute after that, when he hit the crossbar.

Karim Bellarabi, who made his debut for Germany the previous Saturday, appeared to wrap up the result with a fine solo effort in the 41st.

But home favorite Timo Werner pulled one back in the 57th, Florian Klein scored ten minutes later, and Martin Harnik completed an unlikely comeback in the 76th.

Max Kruse scored twice for 'Gladbach in Hannover. The Germany substitute headed inside the far post in the 14th, Granit Xhaka made it 2-0 with a fiercely struck free kick in the 49th, and Thorgan Hazard set up Kruse's second in the last minute.

Wolfsburg midfielder Daniel Caligiuri returned to haunt former side Freiburg. Caligiuri volleyed in Keven de Bruyne's fine cross in the eighth minute, and he sealed Freiburg's fate by adding another in the 66th.

Sebastian Kerk claimed Freiburg's consolation in injury time.

Mainz remains unbeaten after eight games and finds itself provisionally third after a late flurry of activity in the transfer period has reaped reward.

Jonas Hoffman, who arrived on loan from Dortmund, put Mainz ahead in the 20th and former Sevilla winger Jairo Samperio displayed good footwork before scoring on his starting debut three minutes later.

Tobias Werner's 78th-minute header proved only a consolation for Augsburg.