Mikel Arteta has slammed Arsenal winger Nicolas Pepe for his red card during his side's 0-0 draw against Leeds United at Elland Road.
In a cagey encounter in which the woodwork was struck four times in total, the Gunners' efforts were severely hampered when the Ivorian received a VAR-confirmed red card when he head-butted Ezgjan Alioski in the second half.
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Leeds then dominated the remainder of the match but were unable to craft a breakthrough and Arteta believes his player let his team-mates down.
"I never like a draw but in the circumstances it's a point. It (the red card) is unacceptable," he told reporters.
"It is unacceptable. Unacceptable. At this level you cannot do it.
"With 10 men it is a big disadvantage. I really liked the personality of the team when Pepe let the team down, how we stuck to do what we had to do and had a moment or two to win the game, but obviously it makes it really difficult."
While Arsenal were on the back foot for much of the match, Bukayo Saka arguably squandered the best chance of the game after attempting to round Leeds keeper Illan Meslier, who stood his ground to make a good save.
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"It was the best chance in the game, I thought the keeper did well. The reality is they threatened a lot our box and we were lucky on some occasions."
Arsenal have mustered just nine goals from their first nine Premier League games this term and Arteta has admitted that his goal-shy team, who have failed to score in four of their last five domestic engagements, are providing him with a headache.
"It is a concern. You need goals to win matches. We need to create opportunities," added Arteta.
Arsenal vice-captain Hector Bellerin, meanwhile, refused to condemn Pepe, saying the issue will be dealt with internally.
"These things stay in the changing room. After the game everyone has a lot of adrenaline and these things need to wait until later in the week," said the Spaniard.