Bayern Munich hammer Augsburg to kick-off their 'fiery' April, Naby Keita gets RB Leipzig back to winning ways and 'masked finisher' Pierre-Emerick Aubameyang nets in the Ruhr derby.

Here are five things we learned from the 26th round of Bundesliga matches this weekend:

Germany forward Thomas Mueller says April will be a searing examination of Bayern Munich's European, Bundesliga and German Cup title ambitions. Their 6-0 thrashing of Augsburg on Saturday was the first of nine tough games in 29 days for the runaway league leaders. Bayern play third-placed Hoffenheim away on Tuesday, then host Borussia Dortmund next Saturday before facing Real Madrid at home four days later in the Champions League's quarter-final, first-leg. Then comes away matches at Bayer Leverkusen and the Real return leg before hosting Mainz, then Dortmund again, in the German Cup's semi-finals, before finishing the month away to Wolfsburg. "April is a 'hot' month for us, let's see how we come through the fire," said Mueller.

Referee Felix Zwayer missed a clear handball by Borussia Dortmund's Marc Bartra late in Saturday's 1-1 draw against Schalke -- and was shown a red card by the Royal Blues' mascot 'Erwin'. Aubameyang's second-half goal was cancelled out by Schalke's Thilo Kehrer, but home fans in Gelsenkirchen were furious when Zwayer failed to award a penalty after Bartra's handball. Zwayer's red card slipped from his pocket late in the game, so 'Erwin' picked it up after the final whistle and showed it to the official for his performance. "In the moment, with so much tension, I didn't find it that funny," said stern-faced Zwayer. But 'Erwin' is unlikely to face punishment from the German Football Associaiton (DFB) for the prank. "I apologised, it wasn't meant angrily - it was just a bit of fun," said Holger Becker, who was wearing the 'Erwin' costume.

Aubameyang celebrated his goal against Schalke by donning a black and orange mask -- then promptly fell offside with the club's bosses. The Gabon striker has scored 24 goals in as many league games, but his mask was identical to the one he wore while filming 'The Masked Finisher' advert for sponsor Nike. The problem is Dortmund are sponsored by rival brand Puma. Aubameyang already tested the patience of Borussia's chiefs last month by shaving the distinct Nike logo into his hair. "We'll talk about it again, then things will get somewhat harder for him," fumed Borussia's CEO Hans-Joachim Watzke.

Bayern Munich's search to fill the sports director role rumbles on as main candidates Philipp Lahm and Max Eberl have turned the job down. On Saturday, it was confirmed Eberl has signed a contract extension to remain Borussia Moenchengladbach's director of sport until 2022. Likewise, Bayern's captain Lahm last week explained why he will not be the club's director after he retires in June. Germany's top club can not fill the role which has been vacant since Matthias Sammer resigned on health grounds in April 2016. With chairman Karl-Heinz Rummenigge and president Uli Hoeness holding a tight grip on power behind the scenes, Lahm gave a clear clue why Bayern are struggling to fill the role. "Generally, you can only influence things around the team when you have responsibility," he told magazine Stern last week. "I believe Uli Hoeness is still too energetic to let go. He's too young and wants to influence things himself."

RB Leipzig's midfielder Naby Keita collapsed after a Bundesliga match with circulation problems three weeks ago, yet capped his return with two goals in an outstanding display in Saturday's 4-0 win against Darmstadt. A superb strike on a dropping ball saw Keita give second-placed RB an early lead. "Out of 100 players, 99 would not managed that first time, but Naby had the technique and skill to hit it directly," said RB's director Ralf Rangnick. But the reason for Keita's collapse remains a mystery. "It was clear two days afterwards that all his organs were okay," said Rangnick, while the player says he had not "drunk or perhaps eaten" enough before the game.