Eddie Jones has challenged his young England squad to find the hunger that will drive them on to Rugby World Cup glory.
England secured a 2-0 away series whitewash over Argentina with a 35-25 victory in Santa Fe on Saturday, despite being denied the services of up to 30 players.
The two victories ensured that England stayed second in the world rankings, but Jones will not let his squad -- nine of whom are aged 21 or younger -- rest on its laurels.
"Having 30 players out tests your depth," Jones said. "The depth is good but at the World Cup you don't necessarily need your depth all the time. To me it is a great lesson for us that we have to improve and improve rapidly.
"I think the younger players are not hungry enough. I think having had this experience here will make them hungry. I think England players need to be hungrier because they find it too easy.
"They play in the under-20s, they become World Cup champions, they get a contract straight away. That doesn't happen in any other country in the world."
Jones admitted he was disappointed with aspects of the two England performances in Argentina, coming as they did against a pool rival at the 2019 World Cup.
"The biggest thing I have learnt on this tour is that to beat Argentina at the World Cup we are going to have to improve," Jones said. "To win at the World Cup, you need to be bullet-proof, and we're not bullet-proof at the moment.
"In various games they have edged us in certain departments. In the first half they had a set-piece advantage. We can't allow that to happen again. On Saturday we got out of it and the first game we got out of jail a bit. We are too close to Argentina. At the World Cup we need a gap."