With eight South Africans and perennial Major challengers in Oosthuizen and Branden Grace, there was a quiet optimism as the 101st PGA Championship began. Any enthusiasm was swiftly cancelled out by the daunting challenge faced by one of golf’s strongest fields.

Van Rooyen battled a cold putter but his work from tee to green had him under par for much of the opening round until a three-putt bogey on his final hole. The in-form European Tour campaigner was left to rue a back nine that included a couple of bogeys and a double after failing to save from the sand on the par three third.

Joining the former South African PGA Championship winner seven strokes behind defending champion Brooks Koepka was Oosthuizen, the 2010 Open winner.

The 36-year-old struggled early as he went out in two over par before rallying on the back nine with three birdies including a five footer on the last that saw him finish level for his opening effort.

Koepka’s brilliance aside, it was a struggle for the majority of the field with South Africa’s challenge particularly dented. Shaun Norris, Justin Harding and Richard Sterne all face a massive task on Friday if they are to advance past the cut as they sit three, four and five-over par respectively.

Harding’s poor round comes as something of a surprise after he banked a top-10 in last week’s AT&T Byron Nelson.

Richard Sterne’s week is likely already over after he slumped into the clubhouse with a 75.

Tiger Woods, winner of the Masters, and Francesco Molinari, last year's champion golfer, were both two over as they could only watch as playing partner Koepka set about tearing up the course en route to the championship's 17th round of 63.

- ANA