Andy Murray made dealing with the world’s biggest serve look easy on Thursday as he reached the Australian Open third round alongside Ana Ivanovic, who was shaken by an elderly spectator’s courtside fall. Murray, faced with the world record-breaking serve of the physically imposing Sam Groth, had all the answers as he won 6-0, 6-4, 6-1 in just 91 minutes against the flummoxed Australian.