Top-ranked Dustin Johnson's lead shrank from four strokes to two on the front nine in Sunday's final round of the Masters as Australia's Cameron Smith closed in. Johnson birdied the par-4 third but back-to-back bogeys at the par-3 fourth and par-4 fifth, ending a run of 33 bogey-free holes, dropped him back. The lanky American, 0-for-4 when leading majors after 54 holes, responded with six-foot birdie putts at the par-3 sixth and par-5 eighth and made the turn on 17-under. Australia's Smith meanwhile was second on 15-under after a birdie at the par-5 eighth. Smith had birdied the third and answered a bogey at the fifth with a birdie at the seventh. South Korea's Im Sung-jae, birdied the par-5 second and the third and climbed within a stroke of Johnson at one stage, but bogeys at the sixth and seventh answered by a birdie at the eighth left him third on 13-under. Four-time major winner Rory McIlroy, chasing a green jacket to complete a career Grand Slam, made three birdies on the front nine but a bogey to begin the back nine dropped him to fifth on 10-under, one behind South African Dylan Frittelli and seven behind Johnson. js/rcw