England's director of rugby Rob Andrew believes the side have emerged from a "pretty difficult week" with their World Cup campaign back on track.
England withstood a fierce Samoan storm to run out handsome winners
Andrew said England's win over Samoa showed they were moving in the right direction after losing to South Africa.
But the former England fly-half warned against under-estimating Tonga in the must-win clash in Paris on Friday.
"All campaigns are based on dealing with what's in front of you. We've a knock-out game against Tonga," he said.
"We've already played one knock-out game [against Samoa] so we're into that phase early, we're over the first hurdle which was handled very well. Friday night is the only thing that matters now."
England and Tonga are level on points and the winners of Friday's match in Paris will likely qualify as runners-up in Pool A behind South Africa.
The prize then is a probable quarter-final meeting with Australia in Marseille on 6 October.
If you give the island sides momentum, they will cause teams problems
Andrew confirmed "several meetings took place" between coaches and players in the wake of England's 36-0 hammering by South Africa nine days ago.
"Brian (Ashton), the coaches, and senior players in particular, dealt with it very professionally last weekend in a very difficult scenario," Andrew told BBC Radio 5live's Sportsweek programme.
"They've had a pretty difficult week and I think they've handled it very professionally, and got what they deserved.
"Overall you have to be pleased with the final score [against Samoa] - 44-22, four tries, some good rugby.
"But there were still bits of the game the players and coaches will want to improve upon over the next week, and hopefully over the next fortnight.
"Some of the kicking in the second half just put us under a bit of pressure because the one thing the Samoans do very well is run the ball back at you.
We've got more firepower, a good game plan, and England will be nervous
"But there were one or two areas that allowed Samoa back into the game which put the team under pressure for that 10 minutes in the middle of the second half."
Tonga, meanwhile, were leading a second-string South Africa side by 10-7 in the second half of their match in Lens on Saturday before Springbok coach Jake White brought in a raft of first-choice players.
South Africa raced into a 27-10 lead but the spirited Tongans fought back with two late tries before falling to a 30-25 defeat.
"We all know if you give the island sides momentum, ball to play with and opportunities to come at you ball in hand, they will cause teams problems," added Andrew.
Tonga gave the Springboks a real scare on Saturday
"Look at what happened when England played Samoa in the last World Cup - England were losing after 62 minutes.
"You have to give these sides credit because they've some very, very talented footballers."
Tonga have played at all the World Cups except 1991 when they failed to qualify, but have never progressed beyond the pool stage.
"We have one more left, one against England. It's going to be another hard one but if we keep believing in what we have been doing we have a good chance of winning," said Tonga captain Nili Latu.
We needed all our composure to beat Tonga and England will find it hard
Springbok Percy Montgomery
"This is the best Tongan team we have ever pulled out. We got all the players we wanted from overseas teams and we are trying to keep rugby (in Tonga) alive."
Lock Inoke Afeaki, a veteran of the 1995 and 2003 tournaments, added: "(England) struggled to put any points up against South Africa, so we have strengths that they don't have.
"We just need to tidy up our game just a wee bit, there's nothing dramatic we need to put into our game, and I think they (England) will be nervous - they should be.
"We've got more firepower, a good game plan and if they don't turn up and play as best as they can, they know they'll be on the back foot."
Springbok full-back Percy Montgomery, a second-half sub against Tonga, added: "It wouldn't surprise me at all if they were to win. They have had a great World Cup, they are playing attractive rugby and it's a strange game.
"We needed all our composure to beat them and England will find it hard."