Fijian Vijay Singh upstaged his more fancied rivals to take a one-shot lead at the halfway mark of the BMW Championship in Indiana, while Adam Scott is fighting hard in a tie for 13th. Singh backed up his impressive 65 on Thursday with a six-under-par round of 66 at the Crooked Stick Golf Club in Carmel. He sits atop the leaderboard at 13 under, but heavy favourites Rory McIlroy and Tiger Woods are in a tie for second place one shot behind. World No.1 McIlroy endured an eventful round with six birdies and an eagle on the par-five 9th offset by four bogeys in his round of 68. Woods was more consistent with a bogey-free 67 ensuring he will be in the mix over the final two rounds. Scott is five shots behind Singh after back-to-back rounds of 68 and only needs to finish in the top 38 to advance to the season-ending Tour Championship. Geoff Ogilvy dropped off the pace after he could only manage a 71 as he dropped to 33rd place alongside John Senden at five under. Greg Chalmers (even) and Marc Leishman (four over) are well down the leaderboard. Singh hasn&apost tasted success on the PGA Tour since his victory march to the FedExCup title in 2008 and remains cautious heading into the weekend. “I need four days of good playing,” the 49-year-old said. “Sooner or later, I think four days is going to happen, and hopefully it starts this week.” American Ryan Moore is also at 12 under after a second successive round of 66 with seven birdies and just a single bogey on Friday. Englishman Lee Westwood is a further stroke back after a brilliant 65, while Bo Van Pelt is also at 11 under. South Korean Seung-Yul Noh and Canadian Graham DeLaet are tied for seventh at 10 under, while Graeme McDowell is one of four players at nine under.