Arsenal manager Mikel Arteta called it "unacceptable", and said it was a moment that changed the course of his team's Champions League semifinal against Atletico Madrid.

Meanwhile, Atletico coach Diego Simeone's antics as Dutch referee Danny Makkelie studied the sideline monitor at the Metropolitano stadium came under scrutiny Wednesday.

In a white-hot atmosphere and the score locked at 1-1 in Madrid, Makkelie opted to overturn a second-half penalty awarded to Arsenal when substitute Eberechi Eze went down under a challenge from David Hancko.

"The whole sequence tells the story. I mean it's a clear contact," Arteta told TNT Sports. "At this level it's completely unacceptable."

The game ended 1-1 with the second leg set to take place at Arsenal's Emirates Stadium next week.

Arteta said Makkelie had reviewed the penalty incident 13 times before deciding to overturn his decision. Soccer's rules state decisions should not be changed unless there is a "clear and obvious error".

"You make that decision, you cannot overturn that decision when you have to look at it 13 times," Arteta added.

UEFA said the penalty was ruled out because no foul had been committed, despite replays showing clear contact between Hancko and Eze.

TNT Sports panelists Steven Gerrard, Martin Keown and Steve McManaman also disagreed with the Dutchman's decision to overturn the penalty, but they also pointed to Simeone's reaction on the sideline while the official reviewed the video.

"As the referee is coming over, before he's even looked at the screen, Simeone's in his face, he's waving his arms," said former Liverpool midfielder Gerrard. "Then, he's in his ear when he's at the screen. It's a performance, and he's the best at doing it."

McManaman, who played for Atletico's crosstown rival Real Madrid, said of Simeone: "His performance was terrible, and that's why people don't like the dark arts, or don't like Atletico Madrid."

Earlier in the game, Simeone and Atletico players complained about the penalty call that went against their team late in the first half. Viktor Gyokeres put Arsenal ahead by converting from the spot in the 44th minute. Julian Alvarez equalized for Atletico — also with a spotkick — 12 minutes later.

Agencies via Xinhua