Rory McIlroy may be halfway to his fourth Major at the USPGA championship but he still had time to make one young fan’s day at a Louisville gas station.

The new world number one took time out to sign an autograph for Maggie Campbell after his dad realized just who was pulled up in the Mercedes SUV at the pumps.

Dad Timothy Campbell revealed on the blog Vaughts Views how the Irishman took time out to chat with his young daughter after the first round at Valhalla on Thursday.

He wrote: “When Rory made his birdie putt on 18, we left Valhalla. My wife picked the three of us up and we headed toward Louisville on Shelbyville Rd. to fill up the gas tank and get dinner.

“As we pulled into the Thornton’s just down from Valhalla, I noticed someone wearing the same shirt and hat that Rory wore today, did a double-take, and realized it was actually Rory McIlroy.

“He had just stepped out of the driver’s seat of his “PGA Official” Mercedes-Benz silver SUV. He was going to pump the gas himself, but his cell phone rang and he got back in the SUV.

“My wife pulled our car into the gas pump right in front of his. As I hopped out of our car, Rory’s caddy hopped out of the SUV.

“Rory sat in the driver’s seat and finished his call. Maggie got out of our car and I handed her my PGA Ticket and a pen and told her, ‘Now is your chance.’ She didn’t waste it.

“Maggie asked the caddy if she could approach Rory, and he said ‘sure.’ She then motioned to Rory, and he smiled and waved her toward him.

“She said, ‘Hi, I’m Maggie, how are you?’ Rory said, ‘Oh, I’m a little tired, but feel pretty good. I had a good day today (66), could have been better.’

“Rory signed the ticket with a Sharpie pen he had in the SUV. Maggie wished him good luck, and about that time I wandered over with my iPhone camera.

“I said hello and asked if he minded if I took a photo of him and Maggie. He smiled and said, ‘Sure, that would be great,’ in his charming Northern Irish lilt.”

McIlroy’s good form continued on Friday when he shot a second round 67 to open up a two shot lead on Australia’s Jason Day and American Jim Furyk as he bids for a second consecutive Major after his British Open win in July.

He said: “I didn’t get off to the best of starts but I righted the ship well, caught fire a little bit round the turn and am really happy with four under par.

“I’m feeling good about my game, I’m confident and hitting the ball well for the most part. I’m in control of my game and my emotions and I will need to do that over the weekend as well.”

Fellow Ulsterman Graeme McDowell birdied the 17th on Friday to make the cut alongside Offaly’s Shane Lowry but Padraig Harrington and Darren Clarke will miss the weekend.