Manchester United were pushed all the way to extra-time by a stubborn Copenhagen side who were led by their inspired goalkeeper, Johnsson.
The Red Devils were denied a penalty and two goals due to offside calls, rattled the woodwork and registered 14 shots on target, but they eventually broke through via a penalty, after Martial was hauled down in the box, allowing Fernandes to thump home in the first half of extra-time.
United are now through to the last four and will wait to discover if their opponents will be Wolves or Sevilla.
