An extraordinary mid-match pep talk from the chair umpire has fired Nick Kyrgios into a likely US Open third-round blockbuster with Roger Federer in New York.

Swedish official Mohamed Lahyani is already under fire for his unprecedented intervention but Kyrgios rolls on after pulling off a drama-charged 4-6 7-5 6-3 6-0 comeback win over Frenchman Pierre-Hugues Herbert.

Kyrgios was trailing 3-0 in the second set, having thrown away the first on a wild second-serve double-fault, when Lahyani left his chair to beg the Australian to start trying for the sake of the paying crowd and to avoid being sanctioned – again – for not giving his best effort.