CARMEL, Ind. — Roberto Castro kept pouring in birdies and expanding his lead in the BMW Championship until he finished with another 7-under 65 and led by as many as five shots as the other players at Crooked Stick were finishing their rounds.

By the end of the day, U.S. Open champion Dustin Johnson had set the course record at 63 and was tied for the lead.

Johnson was asked to put himself in Castro’s place. If he had never won in 125 starts on the PGA Tour, had a big cushion when he finished Friday, and then saw someone like Johnson charging into the share of the lead, would he be nervous.

“Yeah, I would be, for sure,” Johnson said.

Castro, the Georgia Tech grad who needs a big week just to get home to Atlanta for the Tour Championship, is a practical sort. He’s not as long off the tee as Johnson (not many are) but he’s playing well and golf rewards all manners of good play.

“I think if you look at the tour, it sure helps to be long,” Castro said. “But the guy who is striping it usually wins.”

They were at 14-under 130. Next up is round three:

DUSTIN’S PUTTER: Johnson was getting frustrated by not seeing enough putts fall, so he decided to mix it up and try the TaylorMade Spider. The oversize head of the putter is designed to increase stability. Johnson was asked about the physics behind it, and he wasn’t going there.

“I don’t go into that stuff — as long as it goes where I’m looking,” he said.

The putts were going in the hole, including a 25-foot eagle putt on the 15th and a 30-foot birdie putt on the 14th that sent him soaring to the course record.

Johnson didn’t know he had the course record until Tony Pancake, the golf director at Crooked Stick, informed him.

As for the physics? Johnson says he took a physics course in high school.

“I got an A, too, bud,” he said.

CASTRO AND EAST LAKE: Castro is at No. 53 in the FedEx Cup and figured he would have to win the BMW Championship to be among the top 30 who advanced to the Tour Championship at East Lake, about 15 minutes from where he lives.

It’s not that dire. A fourth-place finish might be enough, depending on other players. Third place would all but secure it.

Castro is just trying to hit fairways and greens, make a putt or two and see where it takes him.

He qualified for the Tour Championship in 2013, and the next year he ended up losing his PGA Tour card.

CASEY’S BACK: Paul Casey is trending in the right direction. One week after he had the 54-hole lead in the TPC Boston (he finished two shots behind Rory McIlroy), he played bogey-free for a 66 on Friday and was three shots out of the lead.

“If you can put it on the right side of the flag, it makes your week really, really easy — or easier,” Casey said. “So I’ve done so far a really good job of that and I would like to continue it over the weekend.”

He is No. 10 in the FedEx Cup. He is No. 22 in the world. He is not eligible for the Ryder Cup because he didn’t want to take European Tour membership, so the FedEx Cup is really the only thing on his mind. That and winning, which Casey hasn’t done on the PGA Tour since 2009.

MOVERS: J.B. Holmes shot a 65 despite a bogey on the last hole. He was four shots out of the lead, and his name on the leaderboard could — or should — only help his cause for becoming a captain’s pick on Monday for the Ryder Cup.

Bubba Watson, the No. 7 player in the world, overcame his fear of blind shots and shot a 67 to tie for 10th. He also needs a captain’s pick. He only cared about two tournaments this year — the Olympics and the Ryder Cup. He was in Rio. He would like to be at Hazeltine at the end of the month.

DJ AND DAY: Jason Day and Johnson are Nos. 1 and 2 in the world ranking. They started 1 and 2 in the FedEx Cup. And they are 1 and 2 in the Vardon Trophy for lowest adjusted scoring average. And they have played together the opening two rounds of all three FedEx Cup playoff events.

The advantage goes to Johnson, who is a collective 13 shots better than Day and sure to take over the Vardon Trophy lead if he keeps it up.