By Mark Lamport-Stokes THOUSAND OAKS, California (Reuters) - Zach Johnson, with his renowned wedge game in sparkling order, soared to the top of the leaderboard with a five-under-par 67 in Thursday's opening round at the Northwestern Mutual World Challenge. Twice a runner-up in the elite 18-player event hosted by world number one Tiger Woods, American Johnson mixed seven birdies with two bogeys to take control on a sun-splashed but chilly day at Sherwood Country Club. Compatriot Matt Kuchar, a double winner on the 2013 PGA Tour, was alone in second after a 68 while five-times champion Woods had to settle for a 71 after missing a three-foot birdie putt at the last. Johnson, who finished second at the 2011 World Challenge, was delighted with his opening round after the scheduled start of play was delayed by frost for an hour. More...