Aryna Sabalenka celebrated her dethroning of Iga Swiatek as the world No 1 with a comprehensive 6-1 6-3 victory over 13th seed Daria Kasatkina in the US Open fourth round on Monday night. Swiatek's defeat on Sunday means Sabalenka will top the rankings for the first time once this tournament is over, although the Australian Open champion's main ambition this fortnight will be to leave with the trophy on Saturday. Sabalenka has made the semi-finals of the past two editions here in New York, and will face Ons Jabeur's conqueror Zheng Qinwen next in her bid to make the last…