England wing Jack Nowell will travel to the World Cup on Sunday despite being struck down with appendicitis while also recovering from his long-standing ankle problem.

Nowell spent four days in an Italian hospital after having his appendix removed last week.

But he has now joined up with the rest of the squad at their Treviso base.

England remain confident he will be fit to play a role in Japan, with their opener against Tonga on 22 September.

"We have no worries there," said assistant coach John Mitchell.

Mitchell says Nowell "needs a good meal" after his illness, but has praised his attitude and energy after returning to camp.

"What I really admire about him is when going through his rehab and the sickness, it doesn't seem to upset him in terms of the energy that he brings to the group," he added.

"He is a good man and we really back Jack."

Nowell hasn't played since damaging ankle ligaments in the Premiership final in June, and has now suffered a series of setbacks in his recovery.

"The ankle is progressing and we expect him to be running pretty soon," Mitchell added.

"The [appendicitis] doesn't help but we still have 20 days until the tournament start and they will be extremely vital for him."

Elsewhere, fellow wing Ruaridh McConnochie "has a shot" of being fit to make his long-awaited debut against Italy in Newcastle on Friday, but centre Henry Slade remains a doubt with his knee problem.

But Mitchell says it is "no major issue" if some players board the plane to Japan without having played any competitive rugby in their warm-up schedule.

"It's all about managing players and the way we train always gives us a very good indication of whether a player can handle the threshold of a Test match," he added.

'Game getting faster and more powerful'

Meanwhile, Mitchell says the game is "constantly changing and evolving" with a number of countries dropping experienced players from their squads on the eve of the tournament.

England have dispensed with the likes of Chris Robshaw, Mike Brown and Danny Care, while New Zealand have left out Owen Franks, Ireland have overlooked Devin Toner, and Wales have jettisoned experienced props Rob Evans and Samson Lee.

"This game is getting more powerful and faster," he explained.

"It's not a personal judgment on any of those guys but unless you can evolve physically with the demands of the game then you are always going to get challenged at some point.

"One thing this game has always taught me is there is no place for self-preservation and it's a tough environment."