Uli Hoeness has returned as Bayern Munich's president, Borussia Dortmund slumped after their midweek Champions League goal fest and new boys RB Leipzig remain unbeaten and top of the league.

Here are five things we learned from the twelfth round of matches in the Bundesliga:

Hoeness returns... and apologises

Despite only having been released in February after 21 months in prison for tax evasion, Uli Hoeness was re-elected as Bayern Munich's president on Friday and the interim seems to have softened him.

The 64-year-old -- who was the only candidate -- received 97.7 percent of the vote in the club's annual general meeting.

He has atoned for his tax sins, but in the euphoria of re-election, Hoeness had declared current Bundesliga leaders RB Leipzig had joined Borussia Dortmund as "Bayern's second enemy".

However, Hoeness showed a softer side by apologising within 24 hours.

"In football -- there are rivals and opponents," Hoeness told Sky before Bayern's 2-1 win over Bayer Leverkusen.

"I'd officially like to take the word 'enemy' back and I apologise for it."

There could be a family reason for Hoeness' apology: nephew Sebastian Hoeness coaches Leipzig's Under 17s.

Dortmund's dodgy defending

"We were deficient technically, tactically and mentally. From the first to the 90th minute," fumed coach Thomas Tuchel after Borussia Dortmund's 2-1 defeat at Eintracht Frankfurt.

Having routed Legia Warsaw 8-4 on Tuesday -- a record score for a Champions League game -- Dortmund's defending was again poor as both Eintracht goals came from restarts.

Hungary midfielder Szabolcs Huszti opened the scoring 16 seconds into the second-half.

Swiss striker Haris Seferovic netted the winner 66 seconds after the restart following Pierre-Emerick Aubameyang's equaliser for Dortmund.

Having heavily rotated his starting line-up, with nine changes for Legia and eight in Frankfurt, Tuchel must fix Dortmund's defensive frailties in January's winter break before they the Champions League's knock-out phase.

Leipzig's Bulls charge on

The 'Bulls', as RB Leipzig are nicknamed, continue their unbeaten charge.

Their impressive 4-1 win at Freiburg on Friday left second-placed Bayern six points adrift before Carlo Ancelotti's side beat Bayer Leverkusen 2-1 on Saturday to halve the advantage.

Leipzig have lost none of their first 12 Bundesliga games - a record for a club in their debut Bundesliga season.

Having been knocked out of the German Cup in the first round last August, Leipzig are only involved in the Bundesliga.

Without having to rotate, coach Ralph Hasenhuettl has used a core of six players who have played in all 12 league games so far.

By comparison, only two Bayern players -- Robert Lewandowski and Manuel Neuer -- have featured in all of Munich's league games.

"Through all of the victories, we are only getting hungrier and there has been a breathtaking development since exiting the cup," said Hasenhuettl.

Leipzig finish the weekend three points clear of Bayern with the teams set to meet at Munich's Allianz Arena on December 21.

Lahm: Bayern's director-in-waiting

Ex-Germany captain Philipp Lahm could be Bayern Munich's director of sport next season.

Having joined Bayern as an 11-year-old, the 33-year-old club captain made his 367th Bundesliga appearance against Leverkusen.

Lahm has a playing contract until June 2018, but looks set to fill the role Matthias Sammer vacated in April.

"We will have, in the not-too-distant future, a director of sport again", revealed chairman Karl-Heinz Rummenigge.

"He has to tick the way Bayern ticks.

"We have someone at the back of our minds, but he's currently still playing."

Lahm told magazine Sport Bild at the start of the month that he may retire from all football at the end of the season and said "talks will take place" when asked about Rummenigge's comments.

Wash clothes, score goals

With seven goals in 12 games, RB Leipzig's top-scorer Timo Werner is a key part of their rise having joined from relegated VfB Stuttgart for 10 million euros ($10.5m).

His two goals in Friday's win at Freiburg was the third time he has scored twice in a Bundesliga game this season.

The 20-year-old says moving leaving the family home for Leizpig improved his game.

"It's made me more confident," he said.

"I have to do my own shopping and the clothes don't wash themselves."