Day dominated Augusta's famous 'Amen Corner' with birdies on holes 12 and 13 before producing one of the great shots of the day, saving par on the 14th after needing to work his way out of the trees from a stray tee shot.
“I had 153 yards to the pin and the wind was in out of the left," Day said of his escape.
"We had about three to four yards of spin with another sevenish yards of hurt. So we are just trying to hit a big high cut.
“Sometimes in those scenarios it’s coming out of first cut, if you contact wrong with it, it can fly straight through and you don’t get the cut. It just comes out like a flyer, so it was important to slice across it.”
Day continued his strong putting form with crucial pars on the 17th and 18th to cap off an excellent day, but with three sunny days expected to further firm up an already dry and fast Augusta course, the 38-year-old is refusing to get ahead of himself.
“If you look down the first fairway you start seeing the purple change. That’s when you know it’s starting to get firm and fast,” Day said.
“If they want, they can definitely soften it out if they need to. If they want single digits to win, it’ll be baked out and fast and guys will be kind of spewing on themselves out there.
“When I see five-under leading, and with what weather we got coming up, I’ve just got to be very patient.
“I’ve just got to just kind of take my birdies when I can and just don’t try and force anything too much.”
“I need to make sure I’m staying on top of my speed because I feel like the greens are only going to firm out and get faster.”
Day's older compatriot, Adam Scott, was one of only 32 players in the field to finish even or better after the opening day, having gone through a rollercoaster morning with five bogeys, three birdies and an eagle on Amen Corner where he was within three metres of the flag after two shots on the par-fiver.
Scott spoke similarly cautiously about the upcoming conditions, echoing the sentiments of other contenders such as Shane Lowry who are anticipating it to be one of the toughest Masters weekends in years.
“It is not right on the edge, but it’s playing nice and firm where you can get yourself in a lot of trouble if you lose control somewhere,” Scott said.
“So I feel all right with today, if it was my off round.
"I would like to get a bit better rhythm going out on the golf course and in my swing for the next couple days and I’ll be right there.”
Cam Smith again struggled with his ongoing inability to transfer his practice form into tournament play as he carded a two-over 74 to be tied for 40th, which would be just inside the cut if repeated tomorrow.
Smith was looking the goods to join compatriot Scott on an even round before fading away with bogeys on the 17th and 18th.
“I’m definitely not out of the tournament,” Smith said.
“It was scratchy today but I feel like I did a pretty good job of getting the most out of it.
“I’m hitting the ball great on the range. I know I’m going to go over there this afternoon and hit five balls and be like ‘where was this all day’,” he said. Just one of those things I think with my game at the minute. I’m just not quite taking it to the golf course.”
The other Australian in the field, Min Woo Lee, has a lot of work to do to extend his tournament into the weekend after carding six over par on Friday morning.
