(Reuters) - Jason Day, who has worked hard to hone a "killer instinct", drained a 35-foot birdie putt on his final hole to take a two-shot lead after Friday's second round of the Arnold Palmer Invitational in Orlando, Florida. One stroke ahead overnight, the Australian world number three was again superb on the greens at Bay Hill needing just 27 putts on the way to a seven-under-par 65 and a 13-under aggregate of 131. Sweden's Henrik Stenson was alone in second after firing a seven-birdie 66, with former U.S. Open champion Justin Rose of England a further stroke back at 10 under, also after a 66. More...