Golf’s man of the moment Adam Scott is poised to complete a summer slam after extending his lead over the Australian Open field to four strokes with a cool third-round 68 at Royal Sydney.

Scott is ideally placed to become only the second man, after Robert Allenby in 2005, to win the Australian Masters, PGA and Open titles in the same season.

Scott’s much-hyped head-to-head duel with Rory McIlroy failed to deliver any real fireworks on Saturday as Australia’s Masters champion tightened his grip on the championship with a minimum of fuss.

The Australian Masters and PGA champion advanced to 16 under for the tournament – and a staggering 51 under par for the summer – with another six birdies as McIlroy struggled to make inroads on Scott’s halfway lead.

After starting the third round two shots adrift of Scott, McIlroy is now four back after carding a two-under 70.  

The Northern Irishman was six behind at the turn after racking up a sloppy double bogey on five when he fluffed two chip shots, but rallied on the back nine to remain Scott’s closest challenger.

The tournament’s headline acts will again face off in the final group on Sunday, with the Open seemingly now a two-man affair.

Matt Jones is outright third but eight six shots off the pace after carding an even-par 72 on Saturday, with Richard Green (73) and Max McCardle (69) equal fourth one stroke further adrift.

Former champion Stuart Appleby is in a four-way tie for sixth at seven under with Nathan Holman (68), Scott Arnold (69) and Leigh McKechnie (71).

Jason Day fired the day’s equal-best round of 66 to climb to six-under and give himself an outside chance of running Scott down with a course-record round on Sunday.

“It’s a long shot but, if I can go out tomorrow and the leaders are not too far away and I shoot a low one, maybe I can catch them,” Day said.

Three amateurs are in the top 20 entering the final round, headed by 18-year-old Anthony Murdaca (66) and Brady Watt (73) at five under.

Ryan Ruffels got to six-under late in his second round, only to stumble with a double-bogey five on the par-3 17th to slip back outside the top 10.

The 15-year-old nevertheless signed off for an impressive 68 to be four-under for the tournament and on track for a big finish in his Open debut.