England's 23-man squad touched down in the luxurious resort of Vale do Lobo in Vilamoura on Monday to begin their preparations for the Brazil finals.
And manager Roy Hodgson said World Cup starting places are up for grabs in the coming weeks.
All 23 squad members, plus standby players Jon Flanagan and John Stones, have been watching videos of their first Group D opponents Italy at their base.
Hodgson wants each and every one of them to be ready for facing the likes of Andrea Pirlo and Mario Balotelli in Manaus.
England play Peru at Wembley Friday week and then take on Ecuador and Honduras in Miami. The three friendly fixtures have taken on greater significance, in light of Hodgson's comments.
"I have many ideas but no firm ideas," Hodgson said when asked whether he knew what team he would send out in Manaus on 14 June.
"Not yet. I don't need to do that yet. We are a long way off. I don't know how the players are going to be performing in three or four weeks' time.
"I don't know how their fitness will be either."