A piece of football sacrilege took place at Old Trafford on Tuesday when Alex Ferguson substituted Giggs 16 minutes from the end of the 1-1 League Cup semi-final first leg draw against Blackburn Rovers.
As Giggs trudged off, the unmistakable sound of booing rang out around Old Trafford.
It came, apparently, from a section of Manchester United season ticket holders unhappy with Giggs's displays at the Theatre of Dreams this season.
For nearly 12 years, the Welsh international has danced his way down the flanks of English club football's finest arena, his twinkling skills leaving would-be tacklers in a dazed heap.
Less than 11 months away from his 30th birthday, Giggs is the club's longest-serving professional, and his United career coincides almost exactly with the most trophy-laden period in their history.
Giggs's personal haul of winners' medals amounts to an Aladdin's Cave of silverware: seven league titles, three FA Cups, one League Cup, one Champions League.
The closest the club have come to another George Best and the finest out-and-out winger of his generation in Europe, Giggs might never have been a United player.
He moved to England from his native Wales aged seven and joined Manchester City's school of excellence. But on his 14th birthday Ferguson snapped up Giggs's signature for United on schoolboy forms and his path was set.
Ferguson handed the waif-like winger his debut in 1991 at the age of 17 and his dribbling skills soon had mouths and full backs' eyes watering throughout the English game.
Until now, the only real criticism aimed at Giggs -- apart from an apparent reluctance to turn out for Wales friendlies -- has been that he does not score enough goals.
His ratio is roughly one every five games, no disgrace for a player whose role is clearly more goal maker than taker, but he has scored only once in the premier league at Old Trafford since August, 1999.
By his own admission, Giggs has fallen short of his own imperious standards in recent seasons.
"Probably the main reason I am getting criticised is that this season, and maybe last, my performances have been better away from home," he told the British media.
Asked to name Giggs's finest moment, most observers would pick out his dismantling of almost the entire Arsenal defence to score the wonder goal that settled an epic 1999 FA Cup semi-final replay at Villa Park.
The goal was a cameo of the kind of magic Giggs brings to football -- an irresistible concoction of speed, close control and balance topped, on that occasion, with an imperious finish.
Giggs's intervention set United on the way to their glorious FA Cup, premier league and Champions League treble that season, but since then the wiry Welshman appears to have entered a period of transition, rather like his club.
That culminated in Tuesday's once unthinkable barracking and a flood of messages, some supportive, some not, on United's official website.
But if Giggs really is a barometer of United's fortunes under Ferguson, those fans who booed him against Blackburn will need to live up to their name and quickly re-unite behind one of the most precious talents the English game has seen.