deft header by Holt but the Spanish keeper was equal to it, not only reaching the effort but clutching it safely.
United were not in top gear throughout the opening 45 minutes but looked dangerous when knitting moves together as Scholes and Michael Carrick tried to get a grip in midfield. After the restart, the Reds asserted more control but there were few chances created.
Bradley Johnson drilled wide following a stray pass out of defence by Evra and Andrew Surman had a volley blocked but the champions' defence looked comfortable. United burst into life with another lovely move as Welbeck played a one-two with Giggs but his lob past Ruddy did not carry enough pace on it and Zak Whitbread was able to clear.
De Gea had to be alert to make a spectacular diving catch to cut out a Pilkington centre but Sir Alex's side conjured up another moment of inspiration when Phil Jones' cross was volleyed against the bar by Giggs, who was so close to marking his special day with a goal.
Nevertheless, the Canaries remained in the game and, after a hopeful penalty shout against Scholes, Holt headed off target when left unmarked inside the area. Evra then blocked a Wes Hoolahan cross at point-blank range and escaped more penalty appeals from the home upporters.
It then took a superb save from De Gea, who pushed away an Aaron Wilbraham drive after the substitute was gifted possession by a rare sloppy pass by Scholes, to keep United level but an equaliser had been on the cards when, seconds later, Holt was allowed to turn despite the close attention of three defenders and lash home after Whitbread's header fell to him.