Jason Day says Royal Melbourne is teetering between playable and very difficult as the already-slick greens quicken during the World Cup.

Day, two shots off the lead heading into Friday’s second round, had to deal with the toughest conditions in the second-last group during Thursday’s first round.

He still shot a three-under-par 68 to be two behind the leaders Thomas Bjorn of Denmark and American Kevin Streelman.

Day said the wind picked up late on Thursday and the greens were also noticeably quicker late in his round.

“The greens on 16, 17 and 18 started to get really firm and started to get really quick out there,” he said.

He said they were already playing faster than those during this year’s US Masters at Augusta National, which is noted for its quick putting surfaces.

“I am not too sure how it is going to be over the next three days,” Day said.

“It was a good test out there for the guys and I thought the course played playable.

“It is kind of teetering on the borderline there of very difficult.”

Day hadn’t expected too much in his first round after a five-week break but was very happy with the way he returned.

Australian teammate Adam Scott, coming off wins in the Australian PGA and Australian Masters, fared much worse.

Scott shot 75, including a quintuple bogey on the par 4 12th.

It left Australia on a combined one over par, six behind the leading teams Denmark and the USA in their push for the World Cup.

But Day tipped Scott would bounce back into contention and said he could only focus on his own game.

“The only thing we can do is just keep playing, play well, both of us need to play well and then we will see at the end of the week,” Day said.