Buoyed by a brilliant eagle from a bunker on the 10th, McIlroy carded a superb third round of 66 to boost his bid to end an eight-year major drought and become the first European winner at St. Andrews since Nick Faldo in 1990.

Only a bogey on the famous 'Road Hole' 17th prevented McIlroy from holding the outright lead, with Norwegian Ryder Cup teammate and playing partner Viktor Hovland, chasing his first major title, also posting a 66 to join the Northern Irishman on 16 under.

"We fed off each other really well," said McIlroy, who also made five birdies as well as his eagle.

"We both put ourselves into a great position going into tomorrow.

"I know I am going to need one more day like the last three days to get the job done."

Rory McIlroy tracks the progress of a drive during his third round. PHOTO: Getty Images.

Queensland’s Cameron Smith had been in pole position after 36 holes after posting a record two-round total of 13 under par, but the World No.6 three-putted the opening hole and made a double bogey on the 13th as he slipped off the pace.

Smith and American Cameron Young will start the final round on 12 under, four shots behind, after rounds of 73 and 71 respectively, with World No.1 Scottie Scheffler and South Korea's Si Woo Kim a stroke further back.

Two-time major winner Dustin Johnson is six shots back following a 71, with Tommy Fleetwood and US Open winner Matt Fitzpatrick on nine under, alongside Australia's Adam Scott.

THE 150th OPEN CHAMPIONSHIP AUSSIE FINAL ROUND TEE TIMES (AEST)

McIlroy lifted the Claret Jug in 2014 and claimed his fourth major in the U.S PGA a month later, but has not won one of the game's biggest titles since.

Augusta National co-founder and three-time Open champion Bobby Jones famously said that a player's career would not be complete without lifting the Claret Jug on the Old Course.

And while McIlroy does not think that is strictly true, the World No.2 was well aware of the significance of winning the oldest major title at the Home of Golf.

"I don't know if a golfer's career isn't complete if you don't, but I think it's the Holy Grail of our sport," McIlroy said in his pre-tournament press conference on Tuesday.

Asked about the significance of winning on Sunday, he added: "It would mean everything because of what I have been through the last few years, trying to get the fifth one."

Viktor Hovland carded a second consecutive 66 to join the lead with a round to play. PHOTO: Getty Images

Even an error-free front nine of 33 – with birdies on the 5th, 6th and 9th holes – had McIlroy a shot behind an inspired Hovland, who had birdied four holes in a row from the 3rd to take over from Smith at the top of the leaderboard.

However, McIlroy then holed out from a bunker short of the 10th green for a stunning eagle to vault into the lead, before Hovland commendably held his nerve to birdie the same hole.

McIlroy found the green in two on the 614-yard par-5 14th to set up another birdie and move into the outright lead, only to then fire his approach to the daunting 17th over the green and off the wall.

The resulting bogey dropped McIlroy back alongside Hovland, who brilliantly saved par from just over the green, with both players then making a birdie on the closing hole.

– Phil Casey