Three Bundesliga clubs could face sanctions from the DFB thanks to the misbehavior of their more radical supporters in the stands. The German football association said on Monday that it had launched investigations against Hamburg, Eintracht Frankfurt and FC Cologne, saying that it expected all three clubs to promptly submit written statements on the incidents. 

Only one of the three incidents had a palpable impact on the pitch. 

When Hamburg supporters let off a smoke bomb early in the game against Darmstadt, the referee was forced to stop play for a few minutes until the air was clear. The smoke wafted on to the pitch, clouding over the goal that Hamburg's keeper Christian Mathenia was guarding. 

Cologne ultras hit Hopp way below belt

To the south and west in Cologne, it was an incendiary message - one the home club stressed it had not approved - that garnered the DFB's attention. 

Fans took aim at the owner of visitors Hoffenheim, SAP software company co-founder Dietmar Hopp. One large banner portrayed a skantily-clad woman holding a handbag labeled SAP in one hand and a piece of paper purporting to be a "birth certificate" in the other. It said: "Name: Dietmar Hopp. Mother: whore. Father: Nazi." 

The Billy Goats' spoting director Jörg Schmadtke called the banner "an insult whose lack of respect cannot be overstated." Cologne's club president Werner Spinner said after the game that he had apologized to Hopp.

"These insults are unacceptable and they do not reflect the values we stand for at FC Cologne," Spinner said. Hoffenheim's Alexander Rosen spoke of a "new dimension of hate." 

Dietmar Hopp, the SAP software mogul who bought the tiny village football club he played for as a kid and propelled it all the way to Germany's top flight, is one of the first symbols of the Bundesliga's new generation of clubs built on corporate cash. To fans of teams like FC Cologne, who like to refer to themselves as teams with "tradition," these newcomers are "plastic clubs."

The issue has arguably been pushed even further to the forefront this season, given the success of Red Bull-backed RB Leipzig. 

Tensions were also high in Cologne with the presence of the right-wing political party Alternative for Germany (AfD), which held its party conference in the city center ahead of September's general election.

The party's presence at the Maritim Hotel was met with protests in Cologne. Another banner under the image, addressed to Hopp, asked: "In the Maritim tomorrow? Your father would be proud." Hopp's father Emil was in the SA during World War II.

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Frankfurt banner against police

Down in Frankfurt, meanwhile, fans took aim at German police - apparently in a bid to protest recent efforts to ban ultras who committed vandalism from the ground. "For every stadium ban... a dead cop!" the message, placed right behind the goal, read. 

Eintracht's board member Axel Hellmann told mass-circulation German daily Bild that the club would be formally apologizing to police. 

"Whatever criticisms you might have of the police in certain instances, this shames us right to the core," Hellmann said.

Eintracht wound up 3-1 winners against Augsburg.

Like Cologne's, and indeed Hamburg's, part of Frankfurt's fan base has something of a reputation in the Bundesliga.