World Number 1 Jason Day will enter his PGA Championship title defence underprepared on the Baltusrol layout.

Jason DayHaving played a busy schedule which has included The Open Championship and his quest to retain the Canadian Open title the past two weeks, Day is playing his third consecutive tournament this week at the year's final Major.

"This week is in a different time slot, but it's still the last major and everyone views it that way," said Day.

"Everyone's trying to win the last major of the calendar year. It's our last shot at glory."

"This is all kind of new to me, even though I have defended before, it's my first Major title defence."

"I won it last year. That was fantastic, and I need to focus on what I need to do this year to win the Wanamaker Trophy again."

Speaking to media on Wednesday, Day mentioned that his practice round, that afternoon, would be the first and last time he would see the course before he tees off in round one.

"I haven't played a practice round. I haven't seen the course. I don't know what it looks like," said Day.

"I was with Doug Steffen, the Head Professional, last night at the champion's dinner. I went through pretty much every hole with him for about 20 to 30 minutes."

"Obviously the prep's been a little on the lighter side. So I need to come in and try to get a good, solid 18 holes in today so I kind of know where I'm going."

While nothing can replace a physical practice round, Day did gain some good insight from Steffen.

"Just certain shots, making sure that I miss it in the right spots, either right or left, if I'm going to miss a fairway," replayed Day of the advice given to him.

"There's some greens out here that you can run them up to, if you hit in the rough, making sure -- like on 4, for instance, the par-3. He said that when the pin location is on the right-hand side, the water kind of cuts in a little bit more. You have to hit it five more yards and it swales down through there because there's a chute coming over the mountain here apparently."

"From what he said, everything breaks away from the mountain just over the clubhouse," added Day, who will still need to devise his own game plan for Baltusrol.

"All that said, I'm going to try and go out there and digest it all, and if that helps, great."

"I really have to go out there and try and find a game plan that works for me and making sure that on the tough holes, I feel comfortable, and the easy holes, I can take advantage of."

"If I can do that, hopefully I'm there by Sunday."

A renowned family man, Day proved again how important family is to him this is week when he spent Tuesday night caring for his wife Ellie.

"I was always going to take Monday off. Dash and Lucy are sick right now, and Dash passed that on to me a little bit. I'm fine. I'm just a little bit under the weather," added Day.

"Ellie had an allergic reaction last night and had to go to the hospital. We were there until two o'clock or something like that. She's fine now. We got a little bit of loss of sleep but we're fine."

Jason Day tees off his Major title defence tonight at 10.30pm AEST playing alongside Phil Mickelson and Rory McIlroy.