Nicholson, whose career was threatened by Chronic Fatigue Syndrome last year, has been given his chance as the more experienced Paul Reiffel and Michael Kasprowicz are currently suffering from injuries.

"I was just blown away when I was told. You never think something like this is going to happen - maybe two years down the track, but not this year," he said.

The 24-year-old has played only seven first-class matches but took seven for 77 in England's first innings in last month's drawn tour match against Western Australia in Perth.

He has also claimed 17 wickets in four Sheffield Shield games this season.

Nicholson, who keeps CFS under control with a strict alcohol-free diet, said: "A lot of the work I've done over the last two years hasn't been so much physical work as discipline and mental work to get myself back up to where I was health-wise.

"It makes all that worthwhile - the nights I was tired and couldn't sleep and all the day I had to get through - this makes it all worthwhile."

Gillespie had been expected to replace off-spinner Colin Miller in Australia's side for the fourth Test, starting in Mebourne on Boxing Day, but has a strained right knee.

England captain Alec Stewart has, meanwhile, demanded that his team show more spirit following the nine-wicket defeat by an Australian XI in their final warm-up match.

Stewart did not play in Hobart but said: "It was totally unacceptable and a few people have to put their hands up and say why."

He added: "The riot act wasn't read but there were a few things pointed out. There will be a very open and honest chat before we start practice tomorrow and you don't have to be too bright to work out what might be said."