Conor Gallagher admits England Under 21s must mature quickly to avoid more scares.
The Chelsea midfielder, 20, helped the Young Lions to a 3-1 win over Andorra at Molineux on Friday.
The visitors threatened a shock after Gallagher, on loan at West Brom, conceded a penalty for Christian Garcia to cancel out Curtis Jones' opener.
Ben Wilmot's header and Callum Hudson-Odoi's penalty earned victory for England and Gallagher knows there is work to be done ahead of Euro 2021.
'He (boss Aidy Boothroyd) always tries to drum into us to think like a 30-year-old,' he said, with England having already booked their spot at next year's tournament.