American teenager Coco Gauff battled into the second round of the US Open on Monday with a stormy three-set victory over German veteran Laura Siegemund. Sixth seed Gauff, seen as one of the favourites for the title after recent tournament wins in Washington and Cincinnati, came from behind to win 3-6, 6-2, 6-4 in an attritional 2hr 50min tussle on the Arthur Ashe Stadium. An ill-tempered match saw Gauff lose her cool with chair umpire Marijana Veljovic in the deciding set, with the 19-year-old accusing the official of failing to enforce time violation rules against Siegemund.