Agassi believes the hardship of several unsuccessful grand slam attempts and the lengths he had to go to to win the US Open last year have made Murray into the player who cannot only compete with Novak Djokovic, Roger Federer and Rafael Nadal, but beat them.

''The way he got across the line in New York will have a huge impact on him moving forward because he had to step up and take it,'' Agassi said. ''He couldn't just wait and watch somebody implode. He had to step up in that fifth set and step up to the biggest situation against the biggest player on the biggest stage and take it, and he did. If his evolution is anything like mine, that was the real light switch that went off for me. I realised that I can't hope for somebody to lose. I have to want this enough to go after it. I think once that clicks in for him, you'll see him playing to their standard throughout the year and for a few years to come.''

Murray's confidence is at a record high following a year in which he upset Federer to win gold at the Olympic Games and overcome Djokovic in five sets to win his maiden grand slam at the US Open. While Agassi admits he was critical of Murray's approach to the game in the past, he believes he has discovered what it takes to win the big matches.

''This is Murray's year to really break through,'' he said. ''I really think his game can play at that standard [of Djokovic, Nadal and Federer]. I think he's slowly come to understand what he needs to do out there as far as not being so passive. He has so many defensive skills that he does run the risk of falling into the temptation of being passive out there on the court. I think that can get him past everybody but not the two greatest players to ever play, not to mention Djokovic, who is now starting to be part of that equation.''

Agassi had to wait two years between his first grand slam triumph at Wimbledon in 1992 and his second at the US Open in 1994. He admitted he allowed complacency to creep into his game after his first success but doesn't think Murray will suffer from a similar after-effect.

''For me, I thought things would come a lot easier and they didn't,'' he said. ''But when I realised that they didn't, I had something to draw on to get me across that finish line. I believe he has very specific goals and objectives. Winning the gold at the Olympics on Wimbledon in front of his home crowd, and being so close at championships, then getting over the line at the US Open, I have to think he believes he can put a lot of numbers on the board.''

Agassi hasn't ruled out Federer but believes Murray and Djokovic are in prime position to make the most of 2013. ''Roger is somebody who can constantly take advantage out of anyone who is not playing their best,'' he said.

''He's 30 years old but I'm out of the business of predicting what he does or doesn't do because he's impressed me so many times. Heading into the year, you really have to look at Murray and Djokovic as the two in the position to raise the standards. Heading particularly towards Australia, I like Andy.''

Is there an Australian Open dark horse? ''Somebody who can put their resume on the table and say, 'I'm ready to go', for me that's [Juan Martin] Del Potro,'' Agassi said. ''You have a guy [playing] some of the best tennis to win a grand slam a couple of years ago, only to be on the sidelines for a year. Whatever time you miss, you can double that time before you're back and slightly better than you were. We're at that time frame now and we're starting to see him play some of the tennis he was before the setback. I think he's in position to be at his best now.''

Twitter -@MichaelChammas