Werder Bremen say they unmasked a Hamburg "spy" who asked for autographs when he was spotted on Wednesday ahead of the two clubs' Bundesliga game on Saturday.
Defeat in the Nordderby at Bremen's Weserstadion would push Hamburg closer to their first-ever relegation from the Bundesliga. Bremen are six points and two places above Hamburg, who Bremen say sent the "spy" to their rivals' open training session earlier this week.
However, smiling Bremen coach Florian Kohfeldt on Thursday revealed that the man had been discovered.
"When we found him in one corner, he asked us if he could have our autographs," Kohfeldt said. "We then agreed to give him what he wants later."
Bremen are level on points with Mainz, who currently occupy the relegation/promotion playoff place, but lost 1-0 at Freiburg last week.
"We've learnt from that match," Kohfeldt said. "That's why, on Saturday, we'll maybe have one or two more solutions."
Hamburg have only 17 points from 23 games and could finally drop to the second tier after having avoided relegation twice in the playoffs in recent seasons.
Meanwhile, 19-year-old Hamburg player Vasilije Janjicic crashed his car while coming out of the Elbtunnel at 160 kilometres per hour and under the influence of alcohol on Wednesday.
Reports alleged that when police was taking down his personal details, he reportedly pretended to be his own twin brother.
"We've told him clearly his behaviour was irresponsible, we won't tolerate it and will sanction it accordingly," Hamburg sporting director Jens Todt told reporters on Thursday.
The crash led to several people being injured and led to the the closure of Autobahn 7 for three hours.