Manchester United headed into the break a goal down courtesy of an eighteenth-minute goal from Robert Lewandowski.
The Polish striker converted from the spot-kick to give the Blaugrana the lead at Old Trafford.
David de Gea got a hand to the ball but the shot was too powerful to keep out.
It was the manner in which the penalty was awarded that would have angered and puzzled United fans.
Bruno Fernandes, who missed an earlier golden opportunity to give the Red Devils the lead, put his hands on Alejandro Balde, who started ahead of Jordi Alba.
The Barcelona star was softly handled at best, before crumbling to the floor in agony at the slightest of contact.
The result was that the referee, Clement Turpin, awarded Barcelona the penalty.
Barcelona were awarded a penalty for this pull from Bruno Fernandes on the arm of Alejandro Balde.
Correct call or harsh decision❓
— Match of the Day (@BBCMOTD) February 23, 2023
Do you agree with this penalty call on Bruno Fernandes? 🤔 pic.twitter.com/CqZjNWhoQj
— ESPN UK (@ESPNUK) February 23, 2023
The decision drew Erik ten Hag’s wrath and the Dutchman made no secret of his disappointment and anger at the questionable call.
Turpin had to walk over and warn the United boss who was up in arms from the touchline.
Another of Turpin’s dubious decisions came just minutes after Lewandowski found the back of the net.
A surging Luke Shaw was powering forward with the ball before he was brought down by Ronaldo Araujo on the edge of the Barcelona box.
The referee saw no reason to stop play and simply waved on for the game to continue.
The controversial decision comes after the initial one at Camp Nou when Jules Kounde fouled Marcus Rashford. Despite it seemingly being the denial of a goalscoring opportunity, nothing was given to the Red Devils.
United fans are not unfamiliar with Turpin. In the three United games the Frenchman has officiated, the Reds have only won once. The most high-profile United game Turpin refereed was the Europa League final lost to Villareal in 2021.