England head coach Eddie Jones says there is no limit to what "kamikaze kids" Tom Curry and Sam Underhill can achieve playing together.
Curry, 21, and Bath's Underhill, 23, are open-side flankers, but Jones has named the Sale man to start on the blind-side in England's World Cup warm-up against Ireland on Saturday.
The pair were supposed to play against Wales on 11 August, but Underhill withdrew with a toe injury.
"There's no ceiling for them," he said.
"As long as they keep the right work ethic, they'll keep getting better.
"Playing two guys who are pretty good at the breakdown might give us an advantage in that area."
The England head coach has also named George Ford and Owen Farrell in the same starting side for the first time in over a year.
Farrell will partner Manu Tuilagi in the centre at Twickenham - something he has never done before in a Test match - as England seek their second warm-up win after losing to Wales last weekend.
Having previously promised to play "fish and chip" classic English rugby, Jones is hoping these changes will help England get to their best.
"Sometimes the opposition team doesn't allow you to put the batter on the fish, so you've got to play a different way," added Jones.
"And then you've got to fry the fish, or grill the fish. So you've got to find a different way of doing it.
"That's all part of the challenge going forward, being adaptable, looking at what's happening in the game and where we can take it."
England play their final warm-up match against Italy on 6 September before opening their World Cup campaign against Tonga in Sapporo, Japan, on 22 September.
Centre Ben Te'o was left out of Jones' World Cup squad last week and brought his England career to an end when he signed a short-term deal with French Top 14 side Toulon on Wednesday.
The 32-year-old, who has 18 caps, is now ineligible for a call-up in the event of injury after the Rugby Football Union reiterated its selection policy with regard to foreign-based players.
It is understood Te'o was involved in an off-field altercation at England's summer training camp in Italy.
"Everyone makes a choice, Ben's made his choice," said Jones. "We wish him all the best and there's not really much more to say on that.
"I've been in contact with his manager. We're happy for him and hope he does really well."
England team to face Ireland: Daly; Cokanasiga, Tuilagi, Farrell, May; Ford, Youngs; Marler, George, Sinckler, Itoje, Kruis, Curry, Underhill, B Vunipola.
Replacements: Cowan-Dickie, M Vunipola, Cole, Lawes, Wilson, Heinz, Francis, Joseph.