CASTLE ROCK, Colo. — Keegan Bradley went from a bundle of nerves waiting to see if he would advance in the PGA Tour postseason to a blissful day of birdies in mile-high air Thursday that led to a 6-under 66 and the lead in the BMW Championship. Bradley, the newly appointed US Ryder Cup captain, was the last man to get in the 50-man field at Castle Pines and he had to sweat it out Sunday.

He was in his hotel room with the TV going, the FedEx Cup standings on another screen and his phone buzzing. “One of the toughest afternoons of my PGA Tour career,” Bradley said. “It was really brutal.

It’s such a relief to be here. I just felt a lot calmer today. But I played really, really well.

” It showed on a course that could dole out punishment without a moment’s notice. Bradley missed only two fairways and two greens, took advantage of the par 5s and made it look relatively easy on the 8,130-yard course, the longest in PGA Tour history. Hideki Matsuyama, the winner in the playoff opener last week, was at 5 under in the middle of the 18th fairway when the opening round was suspended by lightning in the area, a common occurrence during the days of The International at Castle Pines.

Rory McIlroy was just settling over a 20-foot par putt on the 18th when he heard the horn to stop play, smiled and marked his ball. He was likely to wait three hours to putt. Adam Scott, among two players who were at Castle Pines during its two-decade run on the PGA Tour, made a long par-saving p.