It hasn't gone unnoticed that there's been some changes at the top of the men's rankings.

Not only has Roger Federer relinquished the No.1 spot to Rafa (in the process frustratingly missing out by just one week on Pete Sampras' record number of weeks at #1), but the Swiss maestro has quietly slipped to No.3 and is sandwiched between Novak Djokovic and Andy Murray.

These ranking changes have not, however, been without repercussions. They have been the catalyst for a further changing of the guard .... namely in the coaching role in the support teams where there's plenty of action.

Federer has already hired the services of Paul Annacone, the trusted former long serving coach of Pete Sampras. This is a bold step by the Swiss maestro who, at his peak, was in no rush to replace the services of Tony Roche. It will be interesting to see if Annacone can find an extra one or two percent, probably all that's needed for someone technically so close to perfection.

We don't know if Roger is fully recovered from the back injury which plagued him at Wimbledon, but we should find out in New York City, where a healthy Federer would be the bookies' favourite, given it has been somewhat of a hoodoo Slam for Nadal.

The other big move in coaching personnel is with Team Murray, where Andy recently parted ways with Miles Maclagan. It has to be said they achieved much together, namely a US Open and Australian Open final and two Wimbledon semi finals. But I'm sure Andy, quite reasonably, is hoping a change may bring the extra impetus to lay down a Grand Slam victory in the next 12 months.

For some time, Andy has been using the additional services of former world No.2, Spaniard Alex Corretja, who will continue his input. However, this does not seem to be the end game as there is open canvassing for a head coach role, with Aussie Darren Cahill the subject of much speculation.

Darren, mainly known for his stewardship of Andre Agassi in his latter years, certainly has the knowledge and a wealth of experience, especially given what we now know of Agassi's battles with both his self-image and love or otherwise of the sport. But he has ruled himself out overnight, saying he wants to concentrate on his work with Adidas and ESPN.

Todd Martin, whose role with Djokovic ended earlier this year, and Tony Roche have also been mentioned as a potential coach for the Scotsman.

We'll have to wait and see, but I suspect not for too long for a decision to be taken.

So the US Open looms at the end of the month, with much intrigue at the pointy end of the men's game. In the jockeying for a psychological advantage in the coming weeks, it will be fascinating to see the support teams bedded down, and whether the legendary "one percenters" from the changing of the guard will begin to take shape.