"It's tough," The Guardian quotes Murray as saying. "If I had won here [in Melbourne] I would have two slams, a Wimbledon final and Olympic gold and still been well behind Novak.
"The argument a few years ago was with [Caroline] Wozniacki being No. 1 without a slam – but Novak (who won one Grand Slam last year - the Australian Open) still would have been significantly ahead of me even if I'd won. With his consistency just now, Rafa [Nadal] coming back, it's going to get tougher.
"I'll need to do well the next few months and not play badly, especially in the Masters series, I will need to do well there. My next goal is to try and play good tennis in Indian Wells and Miami."
Roger Federer is the current world number two, while Nadal is fifth at the moment.