UEFA have confirmed "at least 5,000 seats" will be closed at the Wanda Metropolitano Stadium for Atletico Madrid's game against Manchester City on Wednesday evening.
The punishment relates to the alleged "discriminatory behaviour" of Atletico fans during the first leg of the Champions League clash at the Etihad last Tuesday, which City won 1-0. The capacity of Atletico's stadium is now expected to be reduced to 63,456. City's allocation for the fixture will not be impacted.
The Wanda Metropolitano Stadium became Atletico's home in 2017 - replacing the now demolished Estadio Vicente Calderon - and hosted the Champions League final between Liverpool and Tottenham in May 2019, which finished 2-0 to Jurgen Klopp's side.
"The UEFA Appeals Body has announced the following decision which would affect the attendance of supporters to UEFA matches," read a UEFA statement on Monday evening.
"To order the partial closure of the Club Atletico de Madrid stadium during the next (one) UEFA competition match in which Club Atletico de Madrid would play as the host club, for the discriminatory behaviour of its supporters.
"Club Atletico de Madrid shall inform prior to the match, the sector(s) to be closed, which shall at least comprehend 5,000 seats.
"To order Club Atletico de Madrid to implement the following directive in the next UEFA competition match which the club shall play as the host club: to display a banner with the wording '#NoToRacism' - with the UEFA logo on it."
This is the second time UEFA have ordered Atletico to close part of their stadium after allegations of racism emerged. A racist banner was spotted among the Spanish club's supporters during their 3-0 Europa League final win against Marseille in 2019.
The news comes after a man was charged by Greater Manchester Police over alleged racist abuse during Atletico's last 16 Champions League tie against City's rivals Manchester United in March. The suspect is Daniel Del Saz Garcia, a 31-year-old from Spain.
"We've charged a man with a racially-aggravated public order offence after a report was made to us at the match at Old Trafford on Tuesday night," read a statement from GMP. "Daniel Del Saz Garcia (31), a resident of Spain, was remanded in custody to appear at Manchester Magistrates' Court today."
A 35-year-old United supporter also told the Manchester Evening News he was racially abused by Atletico supporters during the Old Trafford game. "It was horrible and shocking," he said. "When you see it for yourself you realise that this is real and it is worse than ever.
"It was just disgusting. You can only hope that more action will be taken. Racism is one of the biggest issues in football and it looks like it's not going away. It was horrific and kids were there. The Atletico fans were pretending to peel bananas and eat them in front of black United fans and fans of different ethnicities."