McIlroy earned his first PGA Tour victory at Quail Hollow last month
Rory McIlroy shot an eventful level-par 72 which left him seven shots off the pace in the Memorial Tournament at Muirfield Village in the US.
McIlroy was two under on the 10th tee after two birdies on his front nine but then suffered a double bogey seven at the par-five 11th.
After a birdie on 14, McIlroy suffered another double bogey seven at the 15th.
The 21-year-old undid some of the damage with birdies on 16 and 17 but he dropped a further shot at the last.
Justin Rose, Geoff Ogilvy and Rickie Fowler share the lead of seven under.
Phil Mickelson was two behind Rose and was joined on 67 by Michael Letzig, Rory Sabbatini and Andres Romero.