The match at the Metropolitano was dominated by two VAR decisions, with both teams scoring from the penalty spot in a tense contest ahead of next week's return leg in London.

Arsenal struck first late in the opening half when Viktor Gyokeres converted calmly from the spot after Hancko was judged to have fouled him inside the area. The goal was Gyokeres' 19th of the season and gave the visitors a narrow advantage going into the break.

Atletico responded strongly in the second half and levelled through Julian Alvarez after another VAR review resulted in a handball penalty against Arsenal defender Ben White.

Simeone questioned the first penalty decision and felt the contact on Gyokeres was not enough for a spot-kick at this stage of the competition.

"To award a penalty, it truly has to be a penalty," Simeone said after the match.

"The contact seemed minimal to me in the first half, and we're in the Champions League semi-finals."

Despite Arsenal enjoying long spells of possession, Simeone believed Atletico improved after the interval and deserved more from the game.

"The first half was even. Maybe they were better with the ball but they didn't create many chances," he said.

"In the second half we were better than them."

The Atletico manager also praised the impact of tactical adjustments at half-time, saying his side became more organised defensively while creating opportunities through Antoine Griezmann and Ademola Lookman.

Simeone also provided an update on Alvarez after the forward picked up an injury concern.

"He'll undergo tests. Let's hope it's nothing serious," he said.

He added that Alexander Sorloth had experienced discomfort during the warm-up, which forced Atletico to manage his workload carefully ahead of the second leg.

The Argentine coach reserved special praise for Atletico supporters after a passionate atmosphere inside the Metropolitano.

"Today was incredible. The arrival at the stadium was impressive," Simeone said.

"They won't be present for the second leg, but their souls and hearts will be there."

Arsenal and Atletico Madrid will meet again at the Emirates Stadium on May 5 with a place in the Champions League final still firmly in the balance.

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