Woosie bags first birdie of 78th Masters but finishes with bogeys.
Woosnam's chances of a second Masters title were written off by Rory McIlroy on Tuesday, prompting much laughter in the press conference and a very swift apology from a red-faced McIlroy.
But unsurprisingly, the 56-yearold's share of the lead proved shortlived as he bogeyed the fourth and fifth to drop back to one over par and three off the pace being set by Sweden's Jonas Blixt, who had matched Woosnam's bogey on the fourth but also recorded birdies on the third, fifth and sixth.
But Woosnam was the model of consistency for the next six holes and birdied the eighth to return to level par where he remained through 12.
Unfortunately it was unlucky 13 for Woosie, as his round began to unravel first with a double-bogey, then a bogey, followed by three more bogeys on the last three holes to leave him at five-over par through 18.
That was six shots more than fellow Welshman Jamie Donaldson, who bagged a birdie on the second before dropping a shot on the fourth to return to level par.
After a double-bogey on the seventh it appeared as if Donaldson's round could go the way of Woosnam but birdies on eight, 13 and 14 brought him right back into contention on one under.
Unfortunately further bogeys on 15 and 18 undid some of that good work as Donaldson completed his round on one over, five adrift of clubhouse leader Bill Haas on four under.
Haas carded an opening 68 to finish one in front of defending champion Adam Scott from Australia and two shots ahead of Gary Woodland, KJ Choi, Brandt Snedeker and rookie trio Blixt, Kevin Stadler and Jimmy Walker.
Scott had been four under par after a flawless opening 11 holes, with one of his birdies coming on the par-four 10th where he sealed victory on the second hole of a play-off with Angel Cabrera last year.
But the Australian - aiming to join Jack Nicklaus, Nick Faldo and Tiger Woods in winning back-toback titles - then dumped his tee shot on the 12th into Rae's Creek in front of the green to run up a double-bogey five, before three-putting from long range for par on the 13th and 15th.
Three groups ahead, Miguel Angel Jimenez was also four under after 10 holes as he looked to become the oldest winner of any major championship, Julius Boros being 48 years four months and 18 days when he won the US PGA Championship in 1968.
But the 50-year-old Spaniard then dropped a shot on the 11th and also found water off the tee on the 12th to card a double bogey.
Scott had made the ideal start to the defence of his title as the 78th Masters got under way in perfect conditions, the 33-year-old making the most of seeing his tee shot on the first narrowly miss a deep fairway bunker by firing a brilliant approach to within three feet of the hole.
Scott duly holed out for a birdie and although he failed to birdie the par-five second after his approach found a greenside bunker, the world number two then picked up further birdies on the sixth, eighth and 10th.
Playing partner Matt Fitzpatrick got off to a nightmare start with a double-bogey six, the US Amateur champion driving into trees and then pitching over the green with his third shot.
However, the 19-year-old from Sheffield hit back with a birdie on the second and remained one over par until bogeys on the 13th and 14th.
Pre-tournament favourite McIlroy had been in danger of dropping a shot on the first after spinning his approach back off the green, but almost holed his pitch and was left with a tap-in to save par.
The 24-year-old also made par on the second after finding the same bunker as Scott, but holed from five feet for birdie on the third and also birdied the fifth.
McIlroy fell back to level par after a bogey on the eighth and threeputt bogey on the 12th, but birdied the 13th to get back under par and went two under after another on the 15th.
And with two further pars it looked as if the Northern Irishman would be right in the mix come the end of the day but a bogey on the last left him on one under for his opening round.
Scotland's Stephen Gallacher had been in outright second after a birdie on the ninth took him out in 33, but the debutant bogeyed the 10th, 11th and 12th, before pulling a shot back on 15.
Scott pulled back a birdie on 14 and a run of four pars to the clubhouse saw him complete his round just one shot behind Haas.
Wales' Ian Woosnam pulls out his putter on the first green as his caddie Ansari Mohamed Muhajiri looks on during the first round of the 2014 Masters <B