The Australian coach and ESPN pundit, who helped put the world No.3 together with coach Ivan Lendl some 12 months ago, was a delighted onlooker as Murray won his maiden slam title at Flushing Meadows in September and feels that maintaining that relationship with his inscrutable Czech mentor is the key to more major honours, possibly including the Australian Open which opens on Sunday.
"I do see a slight difference on the court with his attitude now," said Cahill. "He has spent 12 months with Ivan. He knows exactly what the plan is. This time last year, it was a little bit 'let's look and see how this goes'. But they're 12 months down the road now, they have an Olympic gold medal under their belt, a US Open under their belt, and I see a little bit more swagger on the court. That doesn't mean anything when it come to playing these top guys but it means he's not focusing on that one major; he's focusing now on multiples. There's no question he's capable of winning multiple slams."
Cahill, who coached Lleyton Hewitt and Andre Agassi and now works with Team Adidas, has watched Lendl improve the Scot both mentally and technically, and feels there is far more improvement and achievement to come. Where once it was Rafael Nadal and Roger Federer who exerted a grip at the top of the men's game, Cahill feels this could be the time for the Scot and Novak Djokovic to take a stranglehold on the grand slam season.
"I think stability in a relationship, in a player and coach partnership, is more important than people realise," said Cahill. "There has to be that belief and that trust between the player and the coach. You don't get that from spending a couple of months together; you get that from spending years together. I feel like in the next couple years, if they can stay together, it will only be good for Andy. Obviously the big question mark is the amount of travel Ivan takes on, with his family.
"Two or three years ago in 2010 when Novak was going through the rough spot, Brad Gilbert and myself were asked – if we could go back to coaching – who would we take on at that particular time, and both of us in unison said Djokovic," he added. "We saw the potential for the most improvement of someone in the top 10 and credit to his coach Marian Vajda for getting him to where he is. But I look at Andy Murray's game now a bit the same. Even though he's achieved what he's achieved, there's still an enormous amount of achievement that can come from Murray's game. If he and Lendl stay together the next couple years, I think you'll see him realise a lot of his dreams and win more major championships.
"It's a little difficult for me to comment on the Lendl/Murray partnership because I played a small part in it," said Cahill. "Like everybody else, I'm happy that it worked. But getting any real information out of Ivan is like pulling blood from a stone. Sitting on the outside looking in, there's no question that he's targeted four or five different areas in Andy's game. But we're in unknown territory here for the next 12 months for many, many reasons.
"Novak is really the only sure thing we know at the moment: that he's going to put himself in a position to win majors time and time again. The rest of it we don't – we don't know how Federer is going to be, how good he's going to be. We don't know if Nadal is going to come back. We don't know how much that US Open win is going to help Murray. These two guys [Djokovic and Murray] might be dominating every single major like Nadal and Federer did but it's impossible to put a number on it.
"I just know from Andy's perspective, even though Federer and Nadal were dominating the game a number of years ago, the guy he spent more time thinking about was Novak . . . This was his main rival, his measuring stick for success or failure."
Who knows how much that win over Djokovic at the US Open is going to help Andy in the big situations. At the Australian Open, we get to see that for the first time."