Even before he teed off, European skipper Jose Maria Olazabal left the Dubliner in no doubt that he was not at the top of his list of potential picks and needed to do “extraordinarily well” this week.
Demanding a win, Olazabal added: “He is an experienced player, obviously. But at the moment he has not been able to deliver. Period.”
Leading overnight following a sensational 64, Harrington started at the 10th and promptly bogeyed his first three holes. He then dropped further shots at the 15th and 17th (three putts) to lurch to the turn in five-over 40 — 11 shots worse than he managed in the first round.
Struggling from tee to green and with an ice cold putter holding him back, he missed a two-and-a-half foot birdie putt at the fifth and while he birdied the par-five seventh from 18 inches, he had 33 putts, hit just 10 greens in regulation and finished his day five shots behind clubhouse leader Nick Watney (69) on three under.
Tiger Woods battled a sore back to lurk just three behind Watney on five under with three holes to play, while playing partner Rory McIlroy recovered from four bogeys in his first eight holes with three birdies in the next five to get back to one over.
Elsewhere, Graeme McDowell shot a level par 71 to miss the cut on four over par.
McIlroy, meanwhile, has opted not to play in the PGA Grand Slam in Bermuda in October.
The US PGA champion had already agreed to play in the Volvo Masters in Shanghai, which begins the day after the Grand Slam on October 25.
The Shanghai event is part of a money-spinning few weeks for the double-major winner, who is also scheduled to play the eight-man Turkish Airlines World Golf Final in Turkey alongside Tiger Woods from October 9-12 as well as an exhibition against Woods in China on October 29.
As defending Grand Slam champion, Keegan Bradley is first alternate for Bermuda with Graeme McDowell next in line by virtue of his record in this year’s majors.
Bubba Watson (Masters), Web Simpson (US Open), and Ernie Els (The Open) are expected to tee it up at Port Royal.