Organisers of this week's World Cup have bluntly rejected fears the notoriously challenging Royal Melbourne course could verge on becoming unplayable as the richest golf event ever staged in Australia turns into the weekend.

While most players have been complimentary of the mental and physical test the course has offered over the first two days, Royal Melbourne has beat up on a large portion of the world-calibre field, with only 14 men under par going into the final two rounds.

One of the tournament's headliners, Ireland star Graeme McDowell, admitted the course was ''driving him insane'', however insisted he was loving the challenge of lightning putts and sometimes impossible-to-judge approach shots - comparing it to the type of test you only got at golf's majors. That appraisal was backed up by Denmark's Thomas Bjorn, who leads the individual section of tournament at eight under par, and his closest rival American Kevin Streelman (-7), who added that the pace of the greens seemed as quick as Augusta, the home of the US Masters.

But it was comments from Australian star Jason Day, third at four under, that set off concerns that controlling the pace of putts and the bounce of approach shots could prove impossible as the course continues to deal with the toll of hosting two tournaments in two weeks.

Asked whether he felt the course was verging on being unplayable, Day's response forced Australian PGA tournament director Andrew Langford-Jones to face the media and squash concerns that the organisers could be facing a potential problem over the weekend.

''You look at the ninth hole. G-Mac [McDowell] landed his [approach shot] just on the green and it bounced and rolled 30 paces,'' Day said.

''He was coming in with a short iron so that is a little unfair, where you land it perfect just on the front of the green, and it bounces 30 paces over the back. That is just a little unfair, I think.

''I know they watered the greens last night, and some were a little bit inconsistent. But the course is in great shape. You kind of have to guess on holes how far it is going to bounce … on some holes.''

Langford-Jones admitted the course staff faced challenges this week backing up from the Australian Masters, but said he was surprised at the questions being posed to him.

He said organisers felt the course was ''exactly where we were hoping it would be''.