A 32-14 defeat in front of a sell-out partisan crowd of 8,872 at Rochdale on Monday night leaves the Irish needing to pull off a shock win over Steve McNamara's men in their second group A match at the John Smith's Stadium to keep alive their outside hopes of reaching the quarter-finals.
"We've only been together for 10 days so in a very short space of time we've had to mould a team together,"Aston said.
"We've a short turn-around but we'll dust ourselves down. We'll have a look at it tomorrow, train hard Wednesday, Thursday and Friday and we'll turn up on Saturday.
"If they give 100 per cent commitment and be just a little bit smarter towards the end of the sets, I'm sure we can challenge England.
"England haven't been great of late, have they?"
England, whose coach Steve McNamara was at the game, will be without forward Sam Burgess on Saturday after he was handed a one-match ban for a high tackle on Australia second-rower Sam Thaiday during their 28-20 defeat in Cardiff.
The Fijians, who also ended Ireland's hopes at the last World Cup in 2008, made a tremendous start to Monday's match with two tries in the first 12 minutes and winger Akuila Uate ran in two in 10 minutes in the second half to complete his hat-trick.
"They came out hard and we knew they would," Aston added. "They've quite a number of NRL players and they were always going to be physical and tough.
"We needed to play a bit smarter but up front we had a massive dig. I know they'll turn up every week and have a dig on Saturday and the Saturday after. I'm proud of what they tried to do and we will only get better."
Trailing 32-4 after 72 minutes, Ireland hit back with late tries from winger Damien Blanch and debutant forward James Hassan to gain some respectability.
Aston was delighted with the debuts of NRL-based players Hassan, Brett White, Api Pewhairangi and Rory Kostjasyn.
"James Hassan i s a good young kid who was born in London," he said. "He's a bonus for us. He will be around the Ireland circuit for a number of years, as Api will and one or two of the others.
"Brett White must have been the best player on the pitch by a country mile and I thought Rory Kostjasyn was outstanding as well. They've certainly had a massive impact but some other players stood up as well and did themselves proud."
Fiji, who were cheered by the largest expatriate community outside London, will now take on Australia at St Helens on Saturday looking to spring an upset.
- Sports & Recreation