Rory McIlroy has revealed that he has rarely felt so comfortable on a golf course after extending his Open Championship lead at Royal Liverpool on Friday.

A second successive round of 66 saw the Northern Irishman go four shots clear at the halfway stage, and he believes that his confidence is the key factor in his impressive start to the third Major of the year.

"I just feel like I have an inner peace on the golf course. I'm very comfortable in this position, doing what I'm doing right now," McIlroy told reporters.

"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.

"It's a combination of confidence, 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."

McIlroy will play with Dustin Johnson, who currently occupies second spot, on Saturday.