McIlroy backed up consecutive 66s by shooting a four-under-par 68 on Saturday to move to 16 under par, open a six-shot lead over American and fellow 25-year-old Rickie Fowler and give the Holywood golfer the biggest 54-hole lead in an Open since Tiger Woods at St Andrews in 2000.

Sergio Garcia and Dustin Johnson lie seven shots back on nine under with Edoardo Molinari on eight under but McIlroy will start firm favourite to close the deal and join Woods and Jack Nicklaus as the only men to win three different golf majors by the age of 25.

“I feel very comfortable,” McIlroy said in his post-round press conference. “I was in here last night talking about I'm comfortable in this position. I'm comfortable sort of leading the tournament.

“This is the third night in a row that I'll sleep on the lead. So I'm comfortable. It helps that I've been in this position before and I've been able to convert and I've been able to get the job done.

Comfortable with the position that I'm in, but just really comfortable with my golf game. Comfortable with how I'm hitting it, really comfortable on the greens. I feel like that's been a big help this week.

And I just need to go out there tomorrow and play one more solid round and hopefully that's enough.”

It was not all plain sailing for McIlroy, however, with the 2011 US Open and 2012 PGA champion slow to get out of the blocks, perhaps as a result of the rejigged third-round schedule as the R&A brought forward the tee-times, switching to three-man groups and a two-tee start for the first time in Open Championship history.

Teeing off at 11:01am in the final group at 12 under, four shots ahead of playing partner Dustin Johnson and five ahead of Francesco Molinari, McIlroy opened with a bogey at the first and suffered a two-shot swing as American Johnson birdied, the lead cut to two.

But it would not be Johnson to provide the chase, rather his compatriot Fowler, in the group immediately ahead, who birdied four of his first six holes to get to 10 under. A bogey at the seventh proved a blip as Fowler birdied 10, 11 and 12 to get to 12 under.

McIlroy had started to move into second gear, with his third birdie of the week at the par-five fifth and when he did the same at the par-four 11th he was up to 13 under. Just as soon as Fowler birdied the 12th, hot on his heels came a bogey from McIlroy, his four-foot putt lipping out as he fell back into a share of the lead.

Yet it was Fowler this time who fell away, just as Johnson had earlier in the round. He bogeyed 14, 16 and 17 before rallying at the last with a birdie following an excellent sand wedge from a greenside bunker to tap-in distance, settling for a third-round 68 that had promised a much lower score.

As Fowler faded, McIlroy hit top gear and it was irresistible stuff. He rattled in a 35-foot birdie putt on 14 and then came the remaining par-five holes. At 16, he hit the perfect drive, was on the green in two with a wonderful approach to 15ft, from where he sank the eagle putt.

A bogey followed at the par-four 17th, where McIlroy missed the green with his approach, his chip out of the rough rolling back off the slope of the green to its perimeter from where he two-putted.

With the retreating Fowler and the advancing Sergio Garcia also bogeying that hole, the error was quickly erased, particularly when McIlroy launched another great drive on 18. Even better to come was the approach, sent in from 225 yards to eight feet, earning him a generous ovation from the packed horseshoe grandstand to give him “goosebumps” as he strode to the 18th green.

The successful eagle putt was met with a shake of the clenched fist from a golfer who knew he had the Claret Jug within touching distance.

“I feel like today my patience was rewarded,” McIlroy said. “I didn't get off to the best of starts again, and had a few chances around the turn to maybe make birdies, and I wasn't able to do that and then dropped a shot.

“But then I made a big par save on 13. And then to make that birdie putt on 14 was a bonus. And then obviously the finish speaks for itself. I was just sort of waiting for those two holes. I felt like I was driving the ball well, and if I could drive it on the fairway on 16 and 18, I knew that I would have irons into the greens for my second shots. And to be able to make two threes there coming in was very important, and obviously sets me up nicely for tomorrow.”

Both Darren Clarke and Graeme McDowell produced their best rounds of the week to advance up the leaderboard. The 2011 champion Clarke produced the joint score of the day with Jordan Spieth, a five-under 67 that moved him to five under, where he was joined by fellow Ulsterman McDowell, who carded a 68.

Shane Lowry had got his third round off to a flyer, with four birdies in his first six holes to get to five under. In previous days Lowry's best golf around Royal Liverpool had come on the back nine but Saturday's round was the reverse, the Offalyman coming home with a two-over-par inward nine to end the day with a 70, three under for the week.