Rory McIlroy admitted he was surprised to make such a good start to the Tour Championship just days after becoming a father.
McIlroy welcomed the arrival of his first child with wife Erica, with daughter Poppy born on Monday.
Just days later, the Northern Irishman produced the equal best opening round at East Lake, shooting a six-under 64 to be outright fourth, four shots behind Dustin Johnson and Jon Rahm.
The 31-year-old said his performance in Atlanta was a surprise given the past week.
"Yeah, a little bit," McIlroy said when asked if he was surprised he played so well.
"It just shows you golf is such a mental game, and if you come in with low expectations, that's always how I've played well.
"Whether I don't feel like my game is in a good place or I'm not the favourite coming into a tournament, all that stuff, I feel like that's when I usually play my best and I can play with a bit of freedom, and that's what I did."
Last year's FedEx Cup and Tour Championship winner, McIlroy mixed eight birdies with two bogeys in the first round.
Still, McIlroy said he had other things on his mind on Friday.
"It's like every three hours she [Poppy] is supposed to be fed, so I'm like, okay, there's a feeding coming up," he said.
"But like it's natural. It's natural that in between shots you think about other things, and obviously my mind has been very much on what's going on at home.
"But it is nice to have this little four or five hours to myself to concentrate on my game and sort of get into this stuff.
"I played well. I played really well. I played as good as I have in a long time, and that was very encouraging."