It was harsh luck on Benfica, who were the better team and were deservedly in front through Oscar Cardozo.
But in his 22 seasons as a professional, Giggs has learned many times that you do not always get what you deserve in this game.
And whilst Sir Alex Ferguson could not have been that impressed with his side's performance, with seven players making their first starts this season - but not record signing Dimitar Berbatov, who remained on the bench - he will be happy enough with a point from what, on paper at least, appears to be his side's hardest game in the group phase.
Amid all the plaudits United have received for their flying start to the season, Giggs has been virtually ignored.
The turbulence in his private life contributed to this normally affable character declaring a self-imposed ban on speaking to the media during United's pre-season tour of North America.
He was then ignored when the real action started due to the magnificence of the youngsters eager to claim their own place in Red Devils history.
That he was so obviously off the pace during United's Champions League defeat to Barcelona in May hardly helped and it appeared a quiet final season before he called time on a career unmatched in terms of trophies was ahead of him.
Giggs, evidently, has other ideas.
He may be 37 but his mind is as quick as the day he made his debut, over two decades ago.
With his side trailing and struggling, Giggs picked up possession on the right flank three minutes before the break and shot into the space Benfica had afforded him.
The Welshman quickly transferred the ball on to his favoured left foot, and from 20 yards rasped an unstoppable shot past Artur.
It earned him yet another milestone, as the player to have scored in more Champions League seasons - 16 - than anyone else, this his 27th goal in a competition many think is harder to win than the World Cup.
United celebrated and breathed a huge sigh of relief.
They had started in composed manner but all the assurance withered away as the half proceeded and Benfica gained in confidence.
Old stager Pablo Aimar pulled the strings, Nicolas Gaitan and Cardozo attempted to take advantage.
Both went close, and both were denied by last-ditch tackles.
Eventually the breakthrough came though as Cardozo controlled Gaitan's cross on his chest, before whipping round Jonny Evans and drilling a fine shot past Anders Lindegaard.
After finally being given a chance to transfer some excellent pre-season form onto the competitive stage, conceding United's first goal on enemy territory in this competition since March 2010 was not what Lindegaard would have wanted.
In truth though, the Dane was not to blame.
He was one of seven players making their first starts of the season. And it showed.
Even Wayne Rooney was caught up in the general malaise, showing no evidence of being a white Pele as he was booked for clattering Artur.
Antonio Valencia had shown flashes of his old form and forced his way to the by-line as he charged onto Rooney's return ball at the start of the second half.
Once there, he opted to fizz a cross into the six-yard box rather than provide Giggs or Rooney with a cut-back.
Park did cut the ball back, but not far enough for Rooney, whose brilliant dummy enabled Giggs to get into the box but Artur repelled the veteran on this occasion.
If all this gave the impression of United being in charge, it was a misplaced theory.
Benfica remained dangerous and Lindegaard produced the best save of the match to deny substitute Nolito before Emerson fired wide.
Valencia and Darren Fletcher lasted 67 minutes of their first appearances of the season before former Sporting Lisbon winger Nani and Javier Hernandez were introduced.
If those changes could be put down to fatigue, the decision to swap Fabio with Phil Jones appeared solely to stem the flow of Benfica attacks as Lindegaard again did well to deny Gaitan.
Gradually though, the fire subsided from the home side, allowing United to claim their point.