Goal-scorer Marco Reus admitted Borussia Dortmund's 2-0 Bundesliga win over Mainz on Sunday was overshadowed by the death of an 80-year-old fan in the stadium.

The elderly Dortmund fan collapsed with a suspected heart attack in the south-west stand of Borussia's 81,000 sold-out Signal Iduna Park.

A second fan also collapsed, but was revived on the way to hospital.

Reus scored on 30 minutes, but it meant the second-half was played in a subdued atmosphere as the news circulated.

Japan midfielder Shinji Kagawa netted Dortmund's second on 73 minutes in almost complete silence.

"On the pitch, we had no idea what was going on and were initially irritated by the silence," said Reus.

"Straight after the game, our coach (Thomas Tuchel) came to us and explained what had happened.

"It obviously put a shadow over the game and complement to the fans for the way they behaved."

Once the news sank in after the final whistle, the Dortmund team gathered as the home fans sang an emotional rendition of the club's anthem "You'll Never Walk Alone".

"I have never experienced something like that where the supporters were united in expressing their grief and respect," German FA interim president Reinhard Rauball told Sky.

"I also take my hat off to Mainz for the way they gave their support."

Dortmund's victory leaves them second, five points behind Bayern Munich.

Earlier, ten-man Bayer Leverkusen had an own-goal to thank for ending their four-match winless streak in the Bundesliga in a 1-0 victory over Hamburg.

Hamburg's Sweden midfielder Albin Ekdal slid the ball into his own net after 18 minutes at the BayArena to hand Leverkusen victory.

Leverkusen had Croatia right-back Tin Jedvaj sent off in the dying stages after being shown two yellow cards in quick succession for time wasting, then mocking referee Christian Dingert.

On Saturday, Thomas Mueller and Thiago Alcantara netted twice as leaders Bayern warmed up for Wednesday's Champions League last 16 clash at home to Juventus with a 5-0 win over Werder Bremen.

With second-placed Borussia Dortmund playing Mainz on Sunday, Pep Guardiola's team took the chance to reopen an eight-point gap at the top.

It took Bayern just nine minutes to take the lead at Munich's Allianz Arena as Thiago scored his first league goal since February 2014.

Robert Lewandowski, the league's top scorer with 24 goals, came off the bench to claim Bayern's fourth as Bremen were routed.

Wolfsburg suffered a Champions League hangover with a 1-0 defeat at relegation-threatened Hoffenheim.

Wolfsburg reached the last eight in Europe for the first time in the club's history as Tuesday's 1-0 win at home to Gent sealed a 4-2 win on aggregate in the last 16.

But Dieter Hecking's side were stunned by second-from-bottom Hoffenheim as Andrej Kramaric, on loan from Leicester City, scored after just three minutes.

It could have been more as Kevin Volland had a second-half penalty saved.

The defeat leaves Wolfsburg four points outside the top six while Hoffenheim remain three points from safety.

Hoffenheim's win pushed bottom side Hanover 96 closer to relegation as they suffered a 2-0 defeat at home to Cologne with Leonardo Bittencourt scoring both goals.

Eintracht Frankfurt's new coach Niko Kovac suffered a 3-0 defeat on his Bundesliga debut at Borussia Moenchengladbach to stay in the relegation places.

Gladbach's Lars Stindl, Raffael and Mahmoud Dahoud scored the goals as Gladbach climbed to fourth.

A foul on South Korea midfielder Koo Ja-Cheol in the dying stages of Augsburg's 2-2 draw at Darmstadt led to his side converting a penalty to take a crucial point.

Augsburg are deep in the relegation battle as one of three teams on 27 points and just above the relegation places.

Australia striker Mathew Leckie scored only his second goal of the season as he headed home from close range in mid-table Ingolstadt's 3-3 draw at home to Stuttgart.

On Friday, Hertha Berlin cemented third place in the table with a 2-0 win over nearest rivals Schalke thanks to goals from Niklas Stark and Vedad Ibisevic.