Kevin Na has broken a nearly seven-year winless drought on the PGA Tour, shooting a 6-under 64 Sunday for a five-stroke victory at A Military Tribute at The Greenbrier. Na birdied six of his first 10 holes to open up a big lead over third-round co-leader Kelly Kraft on the Old White TPC in West Virginia.Na's only previous tour win came in Las Vegas in October 2011.