Sir Clive Woodward told The Rugby Club that England's three Autumn Internationals will have a significant bearing on whether they lift the World Cup on home turf in 2015.
Stuart Lancaster's side tackle Australia, Argentina and reigning World Cup champions New Zealand on successive Saturday's this November, clashes you will be able to see live and exclusive on Sky Sports.
Woodward - who guided England to World Cup glory in 2003 - says he has been pleased by the progress his country has made since Lancaster took the reins from Martin Johnson at the backend of 2011.
But the 57-year-old believes the Twickenham side - who have selected a host of young players, including Marland Yarde, Joel Tomkins and Billy Vunipola, for this weekend's meeting with the Wallabies - must start showing their credentials now.
"If England are to have any chance of winning the World Cup these are the games they must win," said Woodward.
"They are a good side and are developing well under Lancaster but you'd like to think they can lay down a marker - and it is crucial that they do.
"I think that two years out from a World Cup every team gets stronger, following a drop off after the last World Cup, plus all of England's opponents know they are playing at Twickenham.
"England have a big advantage playing at home in a big tournament [the 2015 World Cup] but the Autumn Internationals are huge ahead of a big year - which includes the Six Nations and three Tests in New Zealand - and then the World Cup.
Watch England versus Australia on Saturday from 1.30pm on Sky Sports 2, plus for full details of Sky Sports' Autumn Internationals coverage, click here.