Sure enough, a fourth goal duly followed. Phil Jones' dominant header found Giggs, whose threaded through-ball released Chicharito to advance, cut inside and unleash a shot which nicked Hughes, wrong-footed Schwarzer and nestled in the Stretford End goal.
Fulham, to their credit, salvaged a modicum of pride when Hughes escaped Rooney's attentions to powerfully head Ashkan Dejagah's corner past De Gea, ending the hosts' hopes of registering a fourth clean sheet in six games.
United might have mustered a rapid response when substitute Shinji Kagawa fashioned space on the edge of the Fulham area, but the Japanese playmaker skied his effort over the bar. Rooney also had a late fifth ruled out for a perceived foul by Chicharito, but the decision had little bearing on a contest which had long since been finished.
The road to Wembley is renowned for being laden with pitfalls and hurdles. Having breezed into the last 16, there's little doubt that greater challenges await if United are to end a nine-year wait for FA Cup glory.