Memorial: Day two behind leader Johnson

In a battle of the Big Three, Jason Day outplayed Jordan Spieth and Rory McIlroy in round one of the Memorial Tournament, shooting a six-under 66 at the Muirfield Village Golf Club in Dublin, Ohio.

All of them, however, trailed the leader, Dustin Johnson, who opened with an eight-under par 64.

The three top-ranked players in the world are all coming off victories in their previous starts -- Spieth in the Dean & DeLuca Invitational, McIlroy in the Irish Open and Day in the Players Championship.

Day, two shots off Johnson's lead, is tied for third with Danny Lee, Matt Kuchar, Hudson Swafford and David Hearn. Brendan Steele posted a 65 and is in second.

McIlroy, meanwhile, shot a one-under 71. He had a rocky round that included three bogeys and a double bogey.

Spieth shot a two-under 70 and is tied for 44th and six shots off the lead.

Johnson had a round that included 10 birdies and 15 of 18 greens in regulation.

"With me, it has everything to do with the putter," said Johnson. "I've been working pretty hard on the putter, and I feel like it's finally starting to pay off."

Phil Mickelson shot well in the first round, recording a four-under 68 on Thursday. He is tied for 13th with Patrick Reed, Keegan Bradley and Jason Dufner, and four shots off the lead.

Rickie Fowler struggled en route to a three-over 75.