Harrington¿s bid for a third successive major unraveled before he got into his stride. Just 30 minutes into his round the Dubliner ran up a disastrous quadruple bogey nine at the second which saw him plummet down the leaderboard to two-over-par.
There was no real hint of the drama to come when the Open and USPGA champion, parred the first and then slightly pulled his drive down the next. It ran down a slope into the trees, however, and in trying to get down near the green on the par five, Harrington hit a trunk and rebounded further into trouble.
He was forced to take a penalty drop away from the bushes, but his next attempt also hit a tree and went into a ditch.
In fairness the Dubliner rallied with three birdies by the time he reached the turn. From there he immediately dropped two shots at 10 and 11 before getting them back at 13 and 14. After parring in he signed for a second successive 73 to be one-under for the tournament.
McDowell was playing alongside Tiger Woods but the 29-year-old struggled to keep the bogeys off the card and eventually matched Harrington¿s 73 to be on the same one-under mark as his fellow countryman.
Having avoided disqualification late last night, McIlroy set about his primary business of playing golf and today the 19-year-old shot a creditable 71 to get back to level par for the tournament.
It was a steady round for the teenager with two birdies and one bogey on the card before he made 10 straight pars to finish his round.