WASHINGTON (AFP) - Dustin Johnson upstaged Jordan Spieth and Jason Day in the first round of the Memorial Tournament on Thursday, as the 2015 US Open runner-up shot a first round eight-under 64.

The hard-hitting American rolled in 10 birdies for a one-stroke lead over Brendan Steele who is alone in second with a 65.

World No. 1 Day shot a six-under 66 with an eagle, six birdies and two bogeys while two-time major winner Spieth shot a two-under 70 with five birdies. Spieth was in a group with world No. 3 Rory McIlroy and Justin Thomas.

Johnson tallied a pair of twos on his scorecard. He had one stretch of four straight birdies beginning at No. 12 and two with three consecutive birdies. His two bogeys came after he failed to get up and down from beside the green.

"I felt like I played well right out of the gates," he said. "I hit it close on the first three holes and made all of them, so that's always a good way to start your day."

Day, Hudson Swafford, Danny Lee, Matt Kuchar and David Hearn each shot 66 as 79 players are under par following a day with perfect scoring conditions. Day had his best finish here in 2009 when he tied for 27th.

"You just have to pick and choose when you feel comfortable and when you don't feel comfortable and try to attack the course from there," said Day, who plays the Muirfield Village course often. "To be a Muirfield member and to play as poorly as I have in the past is frustrating and disappointing. This is one of the events you want to put on your resume."

McIlroy shot a mixed bag 71 that included three bogeys and a double bogey on the tricky par-three 16th hole. He and Spieth teed off on the back nine.

Spieth made bogey on his final hole, the par-four ninth, after sailing his second shot over the green and into a bunker. Spieth and McIlroy combined for 11 birdies but were undone by mistakes.

The worst part of McIlroy's game was his putting, including a three-putt from 13 feet. "Six birdies is great, but the five dropped shots was the rest of the story," McIlroy said.