-7 J Rose (Eng), R Fowler (US), G Ogilvy (Aus) -5 M Letzig (US), A Romero (Arg), P Mickelson (US), R Sabatini (SA), J Day (Aus) -4 S Marino (US), S O'Hair (US), J Furyk (US), S Levin (US), JB Holmes (US), F Jacobson (Swe)
Selected others:-1 B Davis (Eng) level R McIlroy (NI), T Woods (US) +2 E Els (SA)
Rose is currently ranked 66th in the world
England's Justin Rose is in a three-way tie for the lead after a first-round 65 at the rain-delayed Memorial Tournament at Muirfield Village in Ohio.
Rose, still searching for his first PGA title, made six of his eight birdies in 10 holes for a seven-under par total.
American Rickie Fowler and Australian Geoff Ogilvy matched his score, while Phil Mickelson, who could become world number one if he wins, is two back.
Defending champion, and current number one, Tiger Woods struggled to a 72.
Woods, who has won the Memorial four times, began play after a rain delay of two hours. He missed the fairway with several tee shots and was wayward with his wedges but he rebounded from two early bogeys with successive birdies on nine and 10 to finish level par, alongside Northern Ireland's Rory McIlroy.
"My wedges were horrible," admitted Woods. "But I was encouraged at the way I was able to hit a few shots. The shape, the feel - it was more like I hit the ball last year."
However, the top spot in the world rankings, which he has held for 260 weeks, is under threat from Mickelson who must win the tournament and hope Woods finishes outside the top four to usurp his fellow American.
And the left-hander got off to a great start with a bogey-free 67, which included three birdies in his last five holes.
It marked an instant return to form for Mickelson, who missed the cut at Colonial, as he looks to claim his first victory on the Jack Nicklaus-designed course.
He said: "I told Jack it would really mean a lot to me to win his tournament. This golf course is wonderful.
"The soft greens allow you to attack a lot of the pins. It played a lot longer because the ball wasn't rolling. It was a fun day with a lot of good scoring."
Rose was clearly happy with his own efforts on a course he has previously clinched two top-five finishes, including runner-up to American Kenny Perry two years ago.
"I feel like I've been comfortable with my game for a number of weeks, and I'm not really trying to do anything different," he said.
"This is a tournament that I feel like I should have won, for sure.
"I always feel comfortable when I do get here. I like all the tee shots, and the greens are so pure here that if you do get a putting stroke going, you're going to make some putts."
South African Ernie Els endured a frustrating round, which appeared to be going so well after 33 on the opening nine but was ruined by five bogeys after the turn to give him a score of 74.
Englishman Brian Davis was one under for his first round after carding a 71.