Rory McIlroy finished with four successive bogeys as he made a disappointing start to his US PGA Championship campaign with a four-over par opening round. The 37-year-old, bidding to clinch back-to-back majors after defending his Masters title at Augusta last month, was among the morning starters at Aronimink Golf Club in south-west Philadelphia. McIlroy unravelled with five bogeys on his back nine to fall away from the clubhouse lead which stood at three under par. Starting from the 10th hole, McIlroy made a troubled start with an opening bogey, after having to hack out of the rough, but bounced straight back with a birdie at the 11th. From there it was a run of 10 straight pars for the Northern Irishman, who is chasing a seventh major title which would take him past Sir Nick Faldo’s tally and see him become the most successful European of the modern era.…