On the day when thousands lined the rain-lashed streets of Belfast to pay their respects and say goodbye to George Best, possibly the finest talent to emerge from the British Isles since the Northern Irishman stamped his own mark on Old Trafford.
As United ended the most traumatic and emotive of weeks by recording their biggest Premiership win of the season, it was no surprise that Wayne Rooney should be at the heart of their success.
On his return to action seven weeks after fracturing his cheekbone against Lille, Giggs floated a fine corner into the Portsmouth box, which Paul Scholes, completely unmarked, nodded home from eight yards. Incredibly, it was Scholes' first goal since he netted against Charlton on May 1, 22 matches ago.
The major surprise was that United could not add to the midfielder's effort before half-time. Despite monopolising possession, the Red Devils were unable to breach Portsmouth's beleaguered defences on a second occasion.
Jamie Ashdown produced a couple of fine stops, the best of which saw him race from his goal to block Ruud van Nistelrooy's close-range effort after the Dutchman had been released by Rooney's pass.
Rooney was also off target with a couple of trademark thunderbolts, although it was Park Ji-Sung who was really impressing with his thrusting bursts forward. The South Korean might have bagged his first United goal too but an angled drive fizzed over the bar.
Shapeless and outclassed for long periods, all Portsmouth had to offer was the attacking nous of LuaLua, who tested Edwin van der Sar on a couple of occasions.
With Pompey still only a single goal in arrears, caretaker boss Joe Jordan could have delivered a relatively positive half-time team-talk and the visitors almost caught United with the ultimate sucker punch within second of the restart.
It was hardly a surprise that LuaLua was the architect, dancing through the heart of the home defence before releasing Matthew Taylor, whose low shot needed to be turned away by van der Sar.
Portsmouth flattered to deceive afterwards but were still in the contest until Rooney latched onto Andy Griffin's interception 11 minutes from time. With one swift swing of the right boot, Rooney flashed the ball past Jamie Ashdown to end any hope managerless Portsmouth had of snatching an undeserved point from their trip to the Theatre of Dreams.
Ruud van Nistelrooy's late third only emphasised the hosts superiority.