Johnson holds clubhouse lead

St Andrews - American Zach Johnson set a challenging victory target as he birdied the 18th to finish 15 under par at a nailbiting British Open on Monday.

Johnson, the 2007 Masters champion whose best finish at the British Open is tied sixth in 2013, dropped a shot at the formidable 17th but on the last green a snaking 30-foot putt dropped into the cup to huge roars from the grandstand.

His six-under 66 gave him the clubhouse lead on 273 and he seemed overcome shortly after walking towards the scorers' hut.

Australia's Marc Leishman was also 15 under with two holes to play. American Jordan Spieth, Australian Jason Day and 2010 champion Louis Oosthuizen were a further shot back.