American Jack Sock battled back from a set down to beat qualifier Filip Krajinovic 5-7, 6-4, 6-1 and win the Paris Masters title on Sunday, snatching a place at the World Tour Finals.

Yet when Sinner reaches the point just before he swings his arm to hit the forehand, his racket is pointing in what appears to be a position that will make it hard to get a clean connection.