The England coach has built a reputation on his meticulous planning and preparation, a work ethic which has helped him guide the national side to second in the world Test rankings and broken a five-year losing sequence against Australia in one-day cricket.

He has developed more athletic sides in both formats of the game and brought a new intensity into training, but he admits to being excited about the new challenges ahead of him as England and Australia prepare to become the first sides to encounter substitutes and five-over blocks of fielding restrictions.

"All of it is going to be interesting," enthused Fletcher. "Selection is going to be very difficult and then once play gets going it's going to be very tricky - I believe that's going to make it interesting.

"The main variable was constant with the first 15 overs of fielding restrictions and no thinking had to take place aside from the captain moving a few fielders around, but now there are so many variables and then it becomes very complicated.

"It's going to be tricky and it's going to be some time before a pattern settles if it ever does settle. One day cricket has become predictable and somewhere along the line they had to make changes and this will make it pretty interesting."

In addition to the capacity to introduce a substitute, teams will now have only 10 overs of fielding restrictions at the beginning of the innings but the captain of the fielding side will have the option to introduce two five-over blocks of further fielding restrictions at any time of the innings.

It is all part of an attempt by the International Cricket Council, cricket's world governing body, to try and liven up the middle section of one-day international cricket, which they believe had become predictable.

Fletcher is equally intrigued about the possibilities for substitutes, a factor which will have dominated the selectors' deliberations this weekend before they announce the squad for the Challenge series later on Monday.

The selectors will have to decide whether to bring in additional personnel to take the substitution rules into account and Fletcher added: "We have got to take into consideration these new rules they are bringing into the game - it might have some effect, especially the 12th man thing.

"There are a whole lot of scenarios about this. We have thrown it around in the changing room between myself and Michael Vaughan and the management team had a discussion the other day where we sat down and talked about it.

"It gets more and more complicated when you look at all the scenarios and that's what probably makes it so exciting - if there is going to be all these scenarios it will make the game a lot more interesting."