Five things we learned about the Bundesliga

Here are five things we learned from the 19th round of matches in the Bundesliga:

Lahm demands more tempo

Bayern Munich extended their lead at the top of the table to four points after Saturday's 1-1 home draw with Schalke, but captain Philipp Lahm has demanded the tempo be raised.

Bayern have made a slow start to 2017 with lacklustre 2-1 wins at Freiburg and Werder Bremen before Robert Lewandowski's early goal was cancelled out by an equaliser from Schalke's Naldo at the Allianz Arena.

Now Lahm insists they raise the pace -- or risk an early exit from their Champions League last 16 games with Arsenal and German Cup clash with Wolfsburg on Tuesday.

"We must be aware that we can't act like we did in the last three games, otherwise we will be out in all competitions," fumed Lahm, who made his 500th appearance for Bayern.

Dembele dazzles

Pierre-Emerick Aubameyang netted his 17th Bundesliga goal of the season in Borussia Dortmund's 1-0 win over second-placed RB Leipzig, but said Ousmane Dembele's work on the wing made the difference.

"It was unbelievable the way he set up the goal," enthused Aubameyang.

"The goal belonged to him."

The goal took pressure off Aubameyang, the league's top scorer, who was warned at the start of the week to keep quiet about his future plans after he had said he may leave in June during two recent interviews.

The Gabon striker headed home after teenage French winger Dembele ghosted past RB defenders Willi Orban and Marvin Compper and crossed for Aubameyang to head home on 35 minutes.

Dortmund finished the weekend fourth, eight points behind second-placed Leipzig.

RB Leipzig demand answers

RB Leipzig want to know how a group of their fans, including women and children, were attacked by hardcore Borussia Dortmund 'Ultras' during violent scenes which reportedly hospitalised ten and led to 28 arrests.

Leizpig, who are in their first season in Germany's top flight, said the attacks before kick-off in their 1-0 defeat at Dortmund on Saturday were "embarrassing for the whole of football in Germany".

Dortmund's CEO Hans-Joachim Watzke and president Reinhard Rauball say they will ban any of their fans responsible and the German Football Association (DFB) are sure to investigate.

"The attacks of Dortmund fans against opposing spectators and the police, plus insults and offences against women and children, are not acceptable," said RB Leipzig in a statement.

"We expect from Mr Watzke and Mr Rauball that these scenes, which were committed by several perpetrators, will be fully explained in the interests of the entire Bundesliga."

Bayer's Calhanoglu fiasco

Bayer Leverkusen will meet on Monday to discuss the legal implications of winger Hakan Calhanoglu's four-month ban by FIFA for breach of contract.

The 22-year-old is effectively sidelined for all bar the last few weeks of the season after Thursday's decision from the Court of Arbitration for Sport (CAS), who upheld FIFA's ban.

As a 17-year-old in 2011, the German-born forward signed a preliminary contract with Turkish side Trabzonspor when he had an extension deal with German-club Karlsruher.

As well as the suspension, Calhanoglu must pay Trabzonspor 100,000 euros ($108,000) in compensation.

"There are a lot of questions to settle. What will happen with his training, with his salary? We'll be discussing this with all relevant parties," said club boss Michael Schade.

Champions League debut for Frankfurt?

Eintracht Frankfurt reached the European Cup final in 1960, but are on course to make their Champions League debut next season after leap-frogging Borussia Dortmund to go third on Sunday.

Having lost 7-3 to Real Madrid in the Glasgow final 57 years ago, Nico Kovac's Frankfurt are currently lined up alongside Bayern and Leipzig for a direct Champions League place next season.

Having made the last 32 of the Europa League in 2013/14, a Champions League berth would be a huge step up for Eintracht, led by their burly striker Alexander Meier, the league's top scorer in the 2014/15 season.