By Ed Osmond
ST ANDREWS, Scotland (Reuters) – The second round of the 150th British Open started in light drizzle under grey skies at St Andrews on Friday with American Cameron Young atop the leaderboard following his flawless opening 64.
Young was due to tee off at 1326 local time (1226 GMT)looking to continue the form which brought him eight birdies on his Open debut and a two-shot lead over Rory McIlroy.
Tiger Woods began his second round needing a huge improvement on his opening 78 if he is to make the cut at the venue of two of his three Open titles.
The American 15-times major champion, who carded two double-bogeys as he continued his comeback from serious injuries sustained in a car crash last year, parred the first two holes.
World number one Scottie Scheffler began his second round with a bogey at the first hole to drop back to three under.
American Talor Gooch made a move with two early birdies to get to six under par, South Korean Si Woo Kim got to five under after 12 holes and former world number one Dustin Johnson was four under after eight, level with Briton Paul Casey who collected three early birdies.
World number two McIlroy was among the late starters after shooting a composed 66 to set himself up for a serious tilt at winning a fifth major title, eight years after his last.
At the other end of the tournament, former Open champion Mark Calcavecchia followed up his opening 83 with a round of 82 to prop up the 156-man field at 21 over par.
The 62-year-old American, who won the title in 1989, put his disappointing form to one side as he cheerfully posed for photographs on Swilken Bridge and raised his cap to acknowledge warm applause from the packed galleries around the 18th green.
(Reporting by Ed Osmond; Editing by Toby Davis)