By Matt Smith ABU DHABI (Reuters) - Martin Kaymer tightened his grip on the Abu Dhabi HSBC Golf Championship on Friday, shooting a second-round 67 to move to 13 under par following a flawless morning in the desert. “I can’t even remember how I played in 2011 - I know I didn’t miss many fairways and once you do that you have chances.” Starting one stroke clear of Belgium’s Thomas Pieters on eight under, the world number 12 picked up shots at his third, fourth and ninth holes. More...