McIlroy's previous two major championship victories were both by a remarkable eight shots, further highlighting that when McIlroy is good he is very good, almost unbeatable and capable of blowing apart the game's greatest players.
Under scrutiny today because of some notable second round stumbles after fine opening rounds at stages in his career, McIlroy responded in the best way possible by adding another seven birdies and just the one bogey to move four ahead of Dustin Johnson.
McIlroy was asked about his mindset when he gets on this sort of roll and the atmosphere in which an Open Championship is played.
"I don't know if I can describe it. It's just I feel quite, just like I have an inner peace on the golf course. I just have -- I don't know, just feel very comfortable. I'm very comfortable in this position. I'm very comfortable doing what I'm doing right now. It's hard to describe. I wish I could get into it more often.
"If I'm able to do it a few times a year, that's nice. I think it's a combination of confidence. It's just being mentally strong, mentally aware of everything. But I think it all comes down to if you're confident with your game and you're in control of your ball out there, it makes things a lot easier.
"As I said yesterday you try and enjoy every minute of it, even if sometimes it feels like a bit of a grind and you're working extremely hard to keep it together or try and make some more birdies or whatever it is. But the atmosphere out there is incredible. To be able to play in front of crowds like that is -- you have to enjoy it, really.
"It makes it easier when you are shooting 66s and you are in the lead. Yeah, I've been in this position before in major championships. I haven't been in this position in The Open Championship. I'm just really looking forward to the weekend and hopefully continuing the strong play that you've seen so far."
Johnson who, other than a 4th place finish at the recent US Open has been below his best in recent weeks, found form at just the right time to move within four of the lead with a seven birdie no bogey display, recording the best round of the week to date in the process.
Johnson finished runner-up to Darren Clarke at the Open in 2011 and then 9th in 2012 so has a solid record in the event. He could potentially be McIlroy's greatest threat over the weekend.
The group in a share of 3rd at 6 under and six from the lead includes Sergio Garcia, Francesco Molinari, Rickie Fowler, Charl Schwartzel, Ryan Moore and Louis Oosthuizen.
Garcia's start on day two was a roller coaster of sorts. Bogeys at the 1st and 3rd were split by a hole out for eagle at the par four 2nd. He then added three more birdies, his only blemish coming at the 14th but he is well enough placed as he chases his first major championship victory, eighteen years after playing his very first.
Fowler appears to be coming of age at this level. He finished runner-up to a tearaway Martin Kaymer at the recent US Open, was 8th last week in Scotland and importantly has shown an ability to perform well in Open Championship golf when 5th at Royal St Georges three years ago.
Oosthuizen, a seven shot winner of the event in 2010, has been noticeably missing in action of late, Schwartzel, already a major winner, has never had a top ten at the Open although has played reasonably well of late and Molinari has played good at times this season although missed the cut last week in Scotland.
Adam Scott, who had done so well during the more demanding afternoon conditions yesterday, recovered from a shaky start with birdies at the final two holes for a round of 73 and at 3 under shares the Australian lead with Marc Leishman who also improved over his closing nine for a round of 72.
"It was really, really important to finish with a couple of birdies and put me in good shape for the weekend," said Scott. "Lunch will taste a lot better. If the wind stays up this afternoon, I shouldn't be too far back."
That statement was of course made long before McIlroy finished with his round of 66 and Scott now finds himself a massive nine shots off the pace.
Matt Jones, playing his first Open Championship has done well to be at 1 over and in a share of 43rd position along with John Senden, while Rhein Gibson in his very first major championship has done a great job to make the cut on the number, a position he shares with Jason Day.
Six of the eight Australians therefore have survived to make it through to the weekend and hopefully advance their cause.