Arsenal manager Mikel Arteta was left baffled after his side were denied a penalty in Saturday's 1-1 Premier League draw at Burnley.
Arsenal, pushing for a winner after Pierre-Emerick Aubameyang's opener was cancelled out by Chris Wood, felt they should have had a penalty when the ball struck the arm of Burnley's Erik Pieters in the box after Nicolas Pepe tried to flick it past him.
"I think it's obvious and clear, I think there is no debate about that. If that is not a penalty, then would someone explain what a penalty is in this league," Arteta told reporters after the game.
Arsenal midfielder Granit Xhaka was criticised after his dreadful defensive error led to Burnley's equaliser but Arteta said the Swiss was not to blame.
Xhaka had received the ball from Arsenal keeper Bernd Leno deep in the penalty area, but his attempted pass to David Luiz struck Clarets striker Wood and ricocheted into the net.
"It's what it is, it's the way that we play and the way that I want to play. We just have to know the risk and the rules that we have in certain areas in terms of the type of balls we have to play," Arteta said.
Xhaka apologised for the gaffe.
"I hold my hands up for their goal and I'm sorry for the mistake. That's football and right now I feel just as frustrated as all of you," he wrote on Instagram.
The result left Arsenal in 10th on 38 points from 27 games, nine points adrift of fourth-placed Chelsea.
They face Greek side Olympiacos in the first leg of their Europa League last-16 tie on Thursday.