BERLIN (AP) — 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 matches. It will be just one point if Hamburger SV wins on Sunday.
"It's very, very hard for us. But we have to get through it, there's no way around it," said Dortmund coach Juergen Klopp, whose side has conceded in every domestic game this season. "We have to tighten up, there's no question."
Kevin Vogt put Cologne ahead five minutes before the break, and though Ciro Immobile equalized three minutes after the interval, 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, Max Kruse scored twice as Borussia Moenchengladbach defeated Hannover 3-0 away, Mainz beat Augsburg 2-1, and Wolfsburg won 2-1 at Freiburg thanks to two goals from former Freiburg midfielder Daniel Caligiuri.
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, but defensive problems cost the visitors' 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.
"We pushed hard but you can't concede so naively," Klopp said. "Now you're standing there with nothing in your hands. That's hard."
Bayern had no such problems against the league's bottom side.
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, who 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.
"OK, another three points. Now it's about focusing on the Champions League," Guardiola said.
Bremen became the first side not to have a single shot on goal in 6,495 Bundesliga games since records were first kept in 1993.
"It has nothing to do with the coach," said Bremen general manager Thomas Eichin, defending the under-pressure Robin Dutt. "That was just abysmal, a performance not suitable for the Bundesliga. There's no glossing it up. But we'll turn things around again."
In Stuttgart, Heung-min Son opened the scoring for Leverkusen 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 10 minutes later, and Martin Harnik completed an unlikely comeback in the 76th.
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.