London Irish wing Marland Yarde will make his Test debut on Saturday as England seek a 2-0 series victory over Argentina in Buenos Aires.
Yarde, 21, replaces David Strettle on the left wing and will be joined in the three-quarter line by Bath centre Kyle Eastmond, making a first England start.
It will be England's youngest back division for 14 years.
"It has definitely got an X-factor to it, the backline," England head coach Stuart Lancaster said.
"Marland has shown in training and in the games that he is ready for this chance.
""If you look at the stats at the end of the season and compared all the wingers and back three players, he is right up there in terms of defenders beaten, metres made and line breaks."
Rugby league convert Eastmond, 23, has stepped up from the bench after Billy Twelvetrees was called up by the British and Irish Lions.
Lancaster added: "[Eastmond replacing Twelvetrees] is as close to a straight swap as there can be. They are different physically but Kyle can definitely carry and he can distribute and pass pretty much like Billy can.
"The timing of his passing, the range of passing he has got is exceptional and the challenge is to translate that into a game.
"The way we want to play should allow him to express himself and show those talents in the game and it is the next step for him to prove he can do it."
England won the first Test 32-3 and head into Saturday's showdown aiming to complete their first-ever series clean sweep against the Pumas in Argentina.
The last time England fielded a younger back division was in the 32-31 defeat by Wales at Wembley in 1999. Lancaster's selection on Saturday have won just 34 caps between them.
Yarde will become the 24th new player capped by Lancaster in 19 Tests and Stephen Myler could be the 25th if he comes off the bench at the Velez Sarsfield stadium.
London Irish director of rugby Brian Smith rates Yarde as a better player than Chris Ashton, who has been rested from this tour, and he believes he will go on to win 50 caps for England.
Yarde scored a try on his English debut against the Barbarians in May, and his consistency has impressed Lancaster.
"What strikes me about Marland is his workrate off the ball and his desire to get his hands on the ball," Lancaster said. "He is not the type of guy who is just going to stand on his wing and wait for the ball to come to him."
England scored four tries last week on the back of a dominant forward display in Salta and Lancaster knows they will need a repeat performance to give their backs a platform.
"There's definitely going to be a reaction from Argentina and what laid the foundation for our performance last week was our set-piece," Lancaster said.
"Our scrum was good, our lineout was good, we turned over their lineout and created turnover ball and counter-attacking opportunities."
Prop David Wilson and lock Joe Launchbury have not trained fully this week but both are set to play.
England team: Mike Brown (Harlequins); Christian Wade (Wasps), Jonathan Joseph (London Irish), Kyle Eastmond (Bath), Marland Yarde (London Irish); Freddie Burns (Gloucester), Lee Dickson (Northampton); Joe Marler (Harlequins), Rob Webber (Bath), David Wilson (Bath), Joe Launchbury (Wasps), Dave Attwood (Bath), Tom Wood (Northampton, capt), Matt Kvesic (Worcester), Ben Morgan (Gloucester).
Replacements: David Paice (London Irish), Henry Thomas (Sale Sharks), Paul Doran-Jones (Northampton), Courtney Lawes (Northampton), Billy Vunipola (Wasps), Richard Wigglesworth (Saracens), Stephen Myler (Northampton), Ben Foden (Northampton).