Manchester United started brightly against Barcelona at the Nou Camp as they looked to overturn the 1-0 deficit they faced going into the second leg clash.
After 11 minutes, though, it looked like the tie would be beyond them within a matter of moments as Barca were awarded a penalty.
United midfielder Fred was adjudged to have fouled Ivan Rakitic in the box in a challenge which saw the Barcelona midfielder tumble to the ground.
Referee Felix Brych quickly pointed to the spot, with Lionel Messi expected to dispatch the penalty beyond David de Gea with ease.
However, United earned a reprieve when Brych decided to review his decision using the Video Assistant Referee (VAR) system.
Brych watched several replays of Fred’s coming together with Rakitic as he weighed up whether to overturn the penalty.
And there will have been millions of relieved fans across the planet as the referee returned to the pitch and signalled he had overturned his original call.
Pictures of Fred’s challenge on Rakitic immediately started circulating across the web as supporters tried to work out whether a foul had been committed.