SPRINGFIELD, N.J. – These gentlemen lining up to become the latest first-time major winners are not easily rattled.

How low can they go?

Jimmy Walker and Robert Streb are perched atop the leaderboard heading into the weekend at the 98th PGA Championship. They are 9-under following two rounds at Baltusrol and looking for more.

Before they have an opportunity to hoist the Wannamaker Trophy, a number of marquee players have to be dealt with.

Streb was most impressive, taking advantage of a rain-soaked Lower Course on Friday and shooting an 8-under 63. The list of players who’ve gone that low here in a major championship includes Jack Nicklaus, Tom Weiskopf and Thomas Bjorn.

He finished the round a long way from the clubhouse, rolling in a birdie on the ninth hole.

“I was pretty excited about it,” Streb said. “I was waiting on it to break, waiting on it to break and it finally turned there at the end. It was a great round. I’m happy to be part of the 63-club, I guess.”

Not many spectators were around to celebrate the moment.

“It was pretty noisy for the 15 people who were out there,” Streb said with a laugh. “They obviously knew what was going on. They made a nice little racket when the putt went in.”

Walker struggled to hit the ball straight at times, but a steady hand on the greens helped the 37-year-old with five PGA Tour wins shoot a 4-under 66 in Round 2.

He wasn’t ready to be nervous.

“It’s golf,” Walker said. “It’s what we do every week. I’ve won before. I’ve won a few times. I’ve won different ways. I feel like I’ve done a lot in golf. So this is one more little thing here that I haven’t really experienced before. I’m pretty whupped and I’m going to go home and play with the kids and get them to bed. I’m pretty sure I’m going to fall right asleep and be just fine.”

Jason Day is only two shots back despite fighting off an illness early in the week. The bug forced the defending champion to scale back preparations and expectations.

He got everyone’s attention with birdies at Nos. 8, 9, 10, 12, 13, 14 and 15.

So the question is, will the presence of a player who’s learned how to close on the weekend create stress for the leaders?

“I hope so,” said Day, who is tied for third with Emiliano Grillo, a 23-year-old up-and-comer from Argentina. “That would be nice, but when guys are going to play good, they’re going to play good. You look at Henrik (Stenson) and Phil (Mickelson) at The Open. They kind of ran away with it. Doesn’t matter who you are. These guys are all good out here. They all deserve to be here because of how they played.”

Going forward, Streb plans to remain in his own little world.

“Sometimes playing with these guys, you get caught watching them,” he said. “I’ll just try to stick to what I’m doing and see if I can do a little better.”

There are some interesting characters a couple of clutch swings back.

Stenson likely has more confidence than anyone in that bunch after claiming the British Open at Royal Troon with a dramatic 63 in the final round. The 40-year-old Swede overcame two bogeys early in the round, shooting a 67 on the Lower Course in Round 2 to get to 6-under heading into the weekend.

The game plan isn’t likely to change on the weekend.

“No,” quipped Stenson, who is in fifth place. “I think a 63 on Sunday would work pretty well here, too.”

Henrik Stenson watches his approach shot on the 17th hole during the second round of the PGA Championship golf tournament at Baltusrol Golf Club in Springfield, N.J., Friday, July 29, 2016.

Patrick Reed climbed into contention with a 5-under 65 on Friday, and is tied for sixth at 135.

“I feel like my game is tightening up as the week’s going on,” said the 25-year-old soon-to-be Olympian. “It was nice to see, out of my seven birdies, I think five were pretty much kick-in birdies. It’s nice to hit it close and not feel like you had to make a lot of long putts.”

Rickie Fowler had a birdie-eagle finish to post 68 for the second day in a row and is tied for ninth at 4-under. Jordan Spieth made five birdies, shot a 67 and is tied for 13th at 3-under.

The cutline was 2-over.

None of the locals is playing this weekend.

GlenArbor director of golf Rob Labritz and Quaker Ridge Head professional Brian Gaffney finished up tied for 125th with 7-over totals of 147.