SPRINGFIELD, N.J. (AP) — When the first round of the PGA Championship was over there was plenty to talk about and a whole lot to look forward to.

There was the heat — temperatures in the low 90s with no cooling breezes until late Thursday. There was the surprise leader in Jimmy Walker who posted a 5-under 65 in the morning and the shocking round of 77 from U.S. Open champion Dustin Johnson and the rather surprising 74 from Rory McIlroy.

The course stayed true to its reputation as one where you better drive the ball in the fairway but it still gives players a chance to move up the leaderboard late with closing par-5s on 17 and 18.

Walker was far from a runaway leader with three golfers one stroke back and four more two behind including British Open champion Henrik Stenson. Among the crowd at 68 was defending champion Jason Day and Jhonattan Vegas, who didn't qualify for this tournament until winning last week's Canadian Open.

Some things to look for in Friday's second round:

DYN-O-MITE: Walker, who missed the cut twice in his four events, matched his best round in a major and is leading one of the big four tournaments for the first time.

CHANGING TIMES: The players, including Stenson, who played in the afternoon when the wind kicked up and the greens dried out and got bumpy, will get a chance at Baltusrol in the morning when most of the good first-round scores were posted. Look for someone like two-time major champion Martin Kaymer to come out looking to post a number even better than his opening 66.

SLIM CHANCE: The cut of low 70 and ties will be a target for those who struggled in the opening round. Players like Johnson and McIlroy will be looking for something in the mid-60s just to give them a solid chance of playing on the weekend.

DAY LIGHT: Day is looking to become just the second player since the PGA went to stroke play in 1958 to repeat as champion. Thursday's 2-under 68 was a good sign for the Australian. He failed to break 70 in the opening round of the three other majors so he has a chance at putting himself in a good position for the final two rounds.

CHASING HISTORY: Stenson can put himself in rare company as he is trying to become the first player since Ben Hogan in 1953 to win back-to-back majors at age 40.

HANG ON: The best chances to make up some ground will be the closing par-5s of 17 and 18. They played as the two easiest holes on the course Thursday. Eighteen players went birdie-birdie or better on the two holes with Lee Westwood going one shot better with a birdie on the 649-yard 17th and an eagle on the 554-yard 18th. There was a total of five eagles on 18.