By Tony Jimenez TROON, Scotland, July 14 (Reuters) - Justin Thomas, who shares the same birthplace as the late 'Louisville Lip' Muhammad Ali, produced a special 'Louisville chip' on the way to a four-under-par 67 in the British Open first round on Thursday. The 23-year-old made a cracking start to his debut in golf's oldest major championship, roaring to four-under with birdies at each of the opening four holes. Thomas then had to cling on to his score on the inward half at Royal Troon, by far the most difficult nine-hole stretch on the rugged Ayrshire links. More...