Jason Day believes the back injury that hampered him in the opening round at Augusta could prove a "blessing in disguise" as he seeks to claim a first Masters title.

Day, who has battled back issues throughout his career and had epidurals in the lead up to this event, injured himself just before he was due to tee off on Thursday, when he bent down to kiss his daughter on the practice putting green.

The Australian feared he would be forced to withdraw from the year's first major due to the pain he was suffering, but he nevertheless managed to shoot 70 in the opening round after receiving treatment on the second and fourth tees.

Happily, Day then felt fitter on Friday and a five-under 67 lifted him into a share of the lead alongside Francesco Molinari and Brooks Koepka.

Asked in a news conference if his injury could help him "in a weird way", Day replied: "Yeah, definitely.  Especially at a place like this. A major, you know, Augusta National, the Masters, everything that goes on this week, how big it is, and the distraction of wanting to win this tournament so bad.

"Sometimes it's almost a blessing in disguise ... it just brings down the expectation of going out there and trying too hard.

"Yesterday [Thursday] was great to be able to get through that, and I'm hoping that I can take the same attitude, even though I feel pretty healthy now, into the next two days and play well."

Day, who has finished second and third in previous visits to Augusta, spoke at length about the challenges he has faced due to his back problems.

"Some years are better than others," he said. "Emotions go up and down. Sometimes you can be down and depressed because it feels like your world is kind of crumbling around you, and you don't know if you can come back from injuries.

"It can be very depressing and emotional at times. And then all of a sudden, [you] just somehow pop out of it.

"Sometimes I wake up and I feel like I'm 50, sometimes I wake up and I feel like I'm 70, and sometimes I wake up and feel like I'm 18 again. It just comes and goes, and that's just how it is.

"But I feel a lot more optimistic now today than I did yesterday and, bar some outrageous thing that could possibly happen, I'm hoping that I feel this good going into Saturday and Sunday."