The call came after a video review, and Alvarez converted the penalty with a firm shot for his 10th Champions League goal this season, before being replaced later in the second half with an apparent injury.

Gyokeres' opening penalty was Arsenal's first attempt on target, but both teams had exchanged a few early chances.

Arsenal goalkeeper David Raya had made a nice save on a shot by Alvarez, and Martin Odegaard — who was also substituted later — had his dangerous strike from inside the area blocked by Atletico's defense.

Alvarez led the Atletico attack early on, but the connection with Antoine Griezmann and Ademola Lookman didn't work well until the second half.

Alvarez almost curled in a freekick after the break, and both Lookman and Griezmann had chances shortly afterward. Griezmann struck the post with a shot in the 63rd minute, and Lookman, who had been doubtful to start because of a muscle injury, missed from close range later in the second half.

"We played a very good second half and had the chances to win the match," Atletico coach Diego Simeone said.

Griezmann, who played his last home Champions League fixture with Atletico, was named the player of the match.

The France star will join MLS club Orlando City this summer.