Rangnick in the dock after cup controversy

RB Leipzig sporting director Ralf Rangnick is facing possible disciplinary action after attempting to show referee Felix Zwayer video evidence during the  German Cup second round defeat to Bayern Munich.

The 59-year-old ran onto the pitch at half-time intent on showing Zwayer a replay of a controversial incident.

Zwayer had initially awarded Leipzig a penalty when Bayern's Arturo Vidal brought down Emil Forsberg on the edge of the box. Following protests from the Bayern players and consultation with his assistant, Zwayer then reversed the decision, ruling the incident had taken place outside the area.

Read more: Werner, Forsberg et al keep Leipzig's opponents guessing

"It is normal for sporting directors to talk to referees in a calm and factual manner in situations like that," Rangnick told German tabloid Bild. "That is all I did. But it would have been better to do it in the tunnel."

The German football association (DFB) on Thursday launched an investigation into his actions. Rangnick must now provide a written statement.

Hummels: 'Unsportsmanlike behavior'

"I can't imagine that something like that is allowed or wanted," said Bayern and Germany centre-back Mats Hummels, who tried to prevent Rangnick from reaching Zwayer. "I told Mr. Rangnick that it wasn't necessary and that it was unsporting. I kept the points relatively factual from my side."

Read more: Bayern face double dose of Leipzig

Former Bundesliga referee Peter Gagelmann, now a television expert working for Sky Germany, also gave his thoughts on the incident: "When a member of the club's hierarchy leaves the stands to come onto the pitch and show the referee an incident on his mobile phone, then I find that incredibly poor."

Even Rangnick's colleague, Leipzig coach Ralph Hasenhüttl was less than impressed, saying: "Of course, this is not on. This can lead the referee to think: he cannot approach me like that." 

Mired in controversy 

The rescinded penalty was by far the only reason Leipzig felt aggreived. Shortly after half-time, their star player Naby Keita was shown a second yellow card for tugging Robert Lewandowski's shirt. 

The ensuing dismissal was "justified," as Bayern CEO Karl-Heinz Rummenigge put it. However, Keita himself had been a regular victim of fouls that went unheeded.

Read more: Bayern vs. Leipzig part II

In addition, a whole host of Bayern players could count themselves fortunate not to have suffered Keita's fate. Already on yellow cards, the likes of Arturo Vidal, Joshua Kimmich and Jerome Boateng all escaped with warnings despite subsequently commiting fouls that could have been adjuged bookable offenses on another day.

"An outstanding game was destroyed in an instance. With a bit of tact, you don't need to give Naby the second yellow," said Hasenhüttl. "He was booked for his first foul, but was fouled himself three times without consequence. The double standards in the decisions were very hard to take."