by Dave JAMES Agence France Presse NEW YORK, United States (AFP) — Novak Djokovic was once the sick-note Serb whose undoubted promise was at the mercy of a variety of frustrating aches, pains and assorted strains. But with a third US Open title to go with the Wimbledon crown he secured in July he has matched American Pete Sampras on 14 Grand Slam titles and there is little doubt that the 31-year-old is one of […]