The Denmark striker displayed his "lucky boxer shorts" after scoring the second of his two goals against Portugal but his actions upset the Danish FA and could draw Uefa sanctions
Bendtner celebrated the second of his two goals by displaying the boxer shorts, which were sponsored by betting firm Paddy Power. The Arsenal forward claimed that he had worn the underwear in Denmark's first Euro 2012 match and in games before the tournament.
Uefa regulations, however, stipulate that all kit items worn during the finals must be free of any form of sponsor advertising.
"It is just a pair of lucky boxer shorts that I used in the first game as well and have used before the tournament," Bendtner explained. "I didn't know that I was breaking any rules but I am aware of that now."
The Danish FA is sponsored by Ladbrokes, another bookmaker, and was therefore said to be unhappy with Bendtner's celebrations against Paulo Bento's team.
The Paddy Power Twitter account posted a photo of Bendtner's sponsored underwear shortly after the goal was scored.
"We have spoken to the player and he will not play in those [underpants] against Germany on Sunday," the Danish FA's communications director, Lars Berendt, told Ekstra Bladet.
Denmark remain in contention to qualify for the quarter-finals from Group B despite their loss to Portugal and will face Germany in Lviv on Sunday.