A misfiring and cramping Jannik Sinner admitted on Saturday that he “got lucky” after dropping a rare set before taming American underdog Eliot Spizzirri in furnace-like heat to make the last 16 at the Australian Open. 

The two-time defending champion was broken three times in the first set and six times in total as he laboured to a 4-6, 6-3, 6-4, 6-4 victory on over a lung-bursting three hours and 45 minutes.