Nicolas Pepe says he is "deeply sorry" after being shown a red card in Arsenal's 0-0 Premier League draw with Leeds United on Sunday.
The 25-year-old was shown a straight red after 51 minutes at Elland Road for headbutting Whites defender Ezgjan Alioski.
Gunners boss Mikel Arteta described the winger's actions as "unacceptable" and the Ivory Coast international has now taken to social media to apologise for his conduct.
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"Yesterday I let my team down at a crucial time of the game and there is no excuse for my behaviour," Pepe wrote on Instagram.