CALIFORNIA — Hunter Mahan, who has long relished playing golf on the picturesque Monterey Peninsula, birdied five of his first seven holes on the way to a share of the first-round lead in the Pebble Beach National Pro-Am Thursday. The 30-year-old American fired a sparkling six-under-par 66 in mainly sunny conditions on the hosting Pebble Beach Golf Links, one of three venues being used for this week's PGA Tour event. In pursuit of his sixth title on the US circuit, Mahan mixed seven birdies with a lone bogey to end the day level with little-known Briton Russell Knox, who carded a six-under 64 on the Shore Course at Monterey Peninsula Country Club. South Korean Noh Seung-yul and Japan's Ryuji Imada were among a group of six players knotted at five under while defending champion Phil Mickelson opened with a one-under 69 at Monterey Peninsula. Triple major winner Padraig Harrington of Ireland opened with a level-par 72 at Spyglass Hill while US Open champion Webb Simpson returned a one-over 71 at Monterey Peninsula. Twice Pebble Beach National Pro-Am champion Dustin Johnson made a poor start with a three-over 73 at Monterey Peninsula and former world No. 1 David Duval fared even worse at Spyglass Hill, battling to a seven-over 79. Fisher Jr. joins Sterne on top Trevor Fisher Jr. joined South African compatriot Richard Sterne on 15-under-par to share the halfway lead at the Joburg Open Friday. Fisher had an eagle and seven birdies, including a run of three straight in his back nine, for a 9-under 62 on the West Course at Royal Johannesburg and Kensington Golf Club. Sterne went bogey-free for the second consecutive round for his 7-under 65 on the East Course. They were two of five South Africans in the top six at the European Tour event. Locals George Coetzee and two-time winner Charl Schwartzel moved into contention in the second round to sit three shots and five shots off the lead respectively. Coetzee had an 8-under 64 on the East and Schwartzel a 6-under 65 on the West. — Agencies