But with defender Steven Taylor off the pitch receiving treatment, the home team almost immediately got themselves back on level terms.
Giggs found space down the left and sent over a low cross, Fletcher timing his run to perfection to divert the ball past Given and into the net.
It had been a breathless first 25 minutes and as the tempo of the game began to slow, so did the number of chances on offer.
Ferguson's team have been notoriously slow starters for many a year now and their usually precise, swift counter-attacking was a touch off-key on the opening day.
Martins continued to be a threat and shortly after the break he cut in from the left and forced Van der Sar to make a save.
At the other end Campbell was struggling to make an impression, though he did come to life with one run and shot that forced another brilliant low one-handed save from the ever reliable Given.
But they rarely looked like breaking Newcastle down and Vidic's downward header that looped up on to the bar apart, the visitors saw out the game in relative comfort.
Manchester United boss Sir Alex Ferguson:
"We played well in the first half, and their goalkeeper made several good saves to keep them in the match.
"Our attacking play in the first half was good. But as soon as we lost Ryan Giggs to a hamstring injury and Michael Carrick with an ankle, which is swollen up badly - he'll be out for two to three weeks - we lost a bit of our experience in midfield.
"We had possession of the ball but didn't make it count at times - but in light of the people we had missing, it was a creditable result for us."
Newcastle manager Kevin Keegan:
"That was a good, good performance from us and we thoroughly deserved a point.
"Of course you are going to have to ride your luck when you come to a place like this and we did, but no-one can say we got more than we deserved.
"Newcastle fans will go away saying how they witnessed a team playing for the supporters, playing for the badge, playing for the club - and that's what they deserve.
"There were lots of good things for us to build on but we mustn't get carried away as there are a lot of tough games to come."
Man Utd: Van der Sar, Brown, Vidic, Ferdinand, Evra, Fletcher, Carrick (O'Shea 25), Scholes, Giggs (Possebon 63), Campbell (Rafael Da Silva 80), Rooney.
Subs Not Used: Kuszczak, Neville, Evans, Gibson.
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