South Africa, boasting numerous Super 12 stars, were being tipped by some to win easily and were extremley impressive at times. But Ireland also showed themsleves to be a strong unit, and will rue missed opportunities to win this game.
Michael Bradley's charges came out from the half time talk 14 points behind and came back well, but their mistakes combined with South Africa's more clinical finishing proved decisive.
Early on the sides traded steady penalties, Ireland's Michael Rainey and his South African fly-half counterpart Swys Swart doing the kicking, and after almost quarter of an hour Ireland led 6-3.
Then came the first of South Africa's four tries, Schalk Burger piling over to register the tournament's first. The conversion successful South Africa led 11-6, and soon after it was 18-9 following a breakaway interception try by the speedy Bronwen Buys.
Ireland though were still very much in the game thanks to the steady kicking of Michael Rainey, and even when South Africa scored a fine try through Alshaun Bock on the right the half-time score of 26-12 did not look insurmountable.
The first twenty minutes of the second half saw tight rugby render no points but rather two entrants to the sin bin for ten minutes. Ireland lost impressive scrum-half Fiach O'Loughlin while South Africa lost captain Burger. The game lost rhythm.
With both sides back to a full contingent, however, the match sprang to life once again and Ireland registered eight unanaswered points - a penalty and a Keith Matthews try - to bring the score to 26-20.
South Africa added a penalty, only for Potts' converted try to bring Ireland to within two points, but Rainey's kicking boots having deserted him somewhat and with Ireland's handling letting them down too often, chances to go ahead went begging.
When Alshaun Bock hit the line at pace to go in under the posts in the dying minutes the difference between the sides on the day was underlined.
Ireland will take many positives into the next game, albeit ruing missed chances. South Africa have showed themsleves to be extremely strong, but will know that a successful title defence will only come if they can sustain their intensity for longer periods than they managed in this match.
Already well spoilt, the Iffley Road crowd sat and made merry for two hours while England and Australia made their way to the ground for the day's second encounter.