England's Bonfire Night battle with the All Blacks launches a 14-game countdown to next year's World Cup defence in France.
The demanding programme also features four appointments with South Africa and three Tests against France, yet New Zealand should tell England everything they need to know in 80 minutes at Twickenham on November 5.
Many pundits are predicting a quarter-final demise of the defending world champions, with New Zealand hot favourites to prise the Webb Ellis Trophy from their grasp.
While the All Blacks will arrive in November as Tri-Nations title holders and with their World Cup squad effectively in place, England set out on a first full season under head coach Andy Robinson's new support staff of Brian Ashton (attack), John Wells (forwards) and Mike Ford (defence).
"We play the best team in the world on November 5, and that is going to be a massive litmus test, not just in terms of how far things have progressed with the new set-up, but also how far we need to get to," said Lewsey.
"Even if we beat New Zealand, it doesn't mean we are the best team in the world and everything is hunky-dory.
"With regards to the autumn internationals, results will show how we played, but performances, for me, are absolutely key in terms of seeing where we are.
"With regard to the World Cup, and that is the big goal on the horizon, the most important thing for that is we have a run of games this season when we beat good sides and get a run of consecutive victories which gives you confidence.
"In pressure environments, whether you are playing France or whoever it is in a semi-final in Paris, it means you can win in that sort of environment.
"That is why in 2003 we were successful, because we went down to places like New Zealand and Australia and beat the best. We realised we could beat anyone, anywhere."