Dustin Johnson upstaging Jordan Spieth, Rory McIlroy

DUBLIN, Ohio -- The masses arrived at Muirfield Village Golf Club Thursday morning with one item on their agenda: to see Jordan Spieth and Rory McIlroy go head-to-head in the Memorial Tournament.

The World No. 2 and No. 3 golfers were paired in the same group, along with 30th-ranked Justin Thomas, and teed off on the back nine. And it didn't take long for the roars to reverberate around Jack Nicklaus' course.

Spieth shot 2-under 70, with five birdies and three bogeys. He bogeyed his 18th hole of the day -- the par-4 ninth -- after hitting his second shot over the green and into a bunker.

But he was well behind Dustin Johnson, who set the early pace.

The bomber used his towering drives to blister the course, shooting an 8-under 64. He had 10 birdies, including two 2s. His lone bogeys -- on the par-4 sixth and 17th holes -- came when he failed to get up-and-down from beside the green.

The course record is 61, shot by John Huston in 1996.

Hudson Swafford is second, two strokes back at 6-under.

McIlroy shot a topsy-turvy 71 that included three bogeys and a double bogey on the treacherous par-3 16th hole. Thomas finished at 5-over 77.

Thirty-six golfers in the morning wave of tee times shot under par. Even par is tied for 53rd.

World No. 1 Jason Day, a nearby resident and member at Muirfield Village, teed off in the early afternoon.