Novak Djokovic, fired up by his emotional Olympic Games triumph, targets new Grand Slam records at the US Open from Monday as title rival Jannik Sinner arrives in New York dogged by questions over two positive drugs tests. Defending champion Djokovic can become the oldest Open era champion at the tournament if he secures a fifth title, a record he would share with Jimmy Connors, Pete Sampras and Roger Federer. The 37-year-old would also move to 25 Grand Slam triumphs, taking him clear of the 24 he currently shares with Margaret Court.