(Reuters) - While former world number ones Jordan Spieth and Rory McIlroy made erratic starts, long-hitting American Dustin Johnson charged into an early two-shot lead at the Memorial Tournament in Dublin, Ohio, on Thursday. Taking advantage of pristine conditions with a superb all-round game at leafy Muirfield Village, Johnson racked up 10 birdies and two bogeys in the opening round of the prestigious event hosted by Jack Nicklaus. Americans Jason Bohn and Kevin Streelman opened with 67s, world number two Spieth carded a 70 and third-ranked McIlroy mixed six birdies with three bogeys and a double to return a 71.
