(Reuters) - A late double bogey by world number one Jason Day helped American Dustin Johnson back up his U.S. Open victory with a win at the WGC-Bridgestone Invitational in Akron, Ohio on Sunday. Johnson closed with 66 for a six-under total of 274 and a one-shot victory over American Scott Piercy (70). Australian Day (72) finished three shots behind, equal third with Americans Jordan Spieth (67), Matt Kuchar (66) and Kevin Chappell (67). More...