Andy Murray feels in his best shape since winning Wimbledon last year as he prepares to begin his US Open campaign on Monday.

The 27-year-old has struggled all through 2014 to regain peak form and fitness following back surgery almost a year ago.

Form remains a concern to his fans if not seemingly to the man himself, but fitness-wise Murray could scarcely be happier.

The back pain that lingered through the first part of the season is in the past and the Scot had time after Wimbledon to put some serious work in at a training camp in Miami.

Asked when the last time was he felt so well prepared for a grand slam, Murray said: "Australian Open last year, Wimbledon last year would have been the last two. Obviously I missed the French.

"My back was not great during this event last year. This year, this would be the best prepared I have been coming into a slam.

"I got a great training block over in Miami done, so physically I'm where I would want to be. My body is pain-free, which is good. I feel ready. I feel confident and I'm looking forward to the start."

There have been encouraging signs over the last couple of weeks, with Murray reaching quarter-finals in both Toronto and Cincinnati.

But he would have wanted to go further in both and had chances to do so, failing to capitalise on leads against Jo-Wilfried Tsonga and Roger Federer.

That surely betrayed the lack of big match wins Murray has under his belt in 2014 - he has not beaten a top-10 player or reached a final since Wimbledon last year.

He said: "I have been playing well the last few weeks. I lost to guys who won the events, and had quite big opportunities in both those matches. I feel like I'm playing well. This week has been very good preparation. I'm happy."

Murray freely admits he has been far too up and down this season, mixing performances as good as those at his peak with baffling let-downs.

Wimbledon demonstrated the point perfectly, as he breezed through the first four rounds in imperious fashion only to succumb meekly to Grigor Dimitrov.

But the US Open represents the chance for a clean slate, and Murray said: "I think one of the most important things in sport is to not be too hard on yourself after matches, to be able to move on.

"I was obviously not happy with how the matches (against Tsonga and Federer) ended. I was very disappointed. But it's something that you need to learn to be able to move forward and make sure it doesn't eat into your preparation time or take up mental energy that you might need going into a tournament like this."

Murray begins his campaign against world number 70 Robin Haase, and he knows all too well how dangerous the big-hitting Dutchman can be.

They met in the second round in New York in 2011 and Haase led by two sets to love before Murray staged one of his trademark fightbacks.

The match will be played on Flushing Meadows' second court, Louis Armstrong, where Murray has had many major struggles in the past.

Haase revealed he almost did not play the match three years ago because of a back injury.

"I won my first round just by serving and hitting a few winners," Haase said.

"Against Andy I knew that's not possible to do the same. But somehow he let me actually because in the first two sets he didn't make me run as much.

"Once he did, it was very quickly over the match. I came back (in the fifth set) but I had no chance to win the match.

"It's a long time ago. The last time we played was at the Australian Open (in 2013) where I knew I had no chance to win. I had made some changes, I didn't feel good at that time.

"Now it's a different time for me. I feel much better on the court, now I give myself a much better chance than a year ago."

Haase, who was out of action for a year and a half after knee surgery in 2008, gave a wry smile when asked about Murray's struggles.

Describing his own right knee as that of a 60 or 70-year-old man, Haase said: "I call it a struggle when a guy like me is losing first rounds and second rounds.

"I have never felt right after my knee surgery. Every day I have pain but I love to do what I do and I'm happy I can do it."