McNamara’s men are just hours away from a moment they have been building towards for three years.
McNamara said: “Stick with us is the message, without a doubt. We’ve got a brilliant tournament coming up.
“It was always going to be a roller coaster. There’ll be some bad moments, some good moments, some tough moments – we hit one of those (against Italy) and we’ve got to move on.”
On the shock Italy defeat, he added: “That’s sport, and we deal with that all the time.
“Every single player in our dressing room has been in that situation before, where you’ve lost a game you were expected to win.
“It’s nothing new for that group, and I’m sure supporters and fans have been in that situation. It wasn’t how we wanted it to be last week, but hopefully the outcome will be a lot different this week.”
He said: “We didn’t perform and we got our backsides burned. It was a timely reminder for us as a group and a team that we’re still not a team that can be off our game and win.
“We have to be there or thereabouts at our best in every game to achieve success and that’s something we’ve been striving for.”
And the England boss is adamant that lifting the famous trophy is England’s only goal. Asked whether he would be happy with a semi-final or final spot, he said: “We’re setting out with the aim to try to win it. There are no minimum requirements for me.
“We all know it’s very tough. Winning a World Cup shouldn’t be easy, but I think we’re capable of doing so.”
He added: “To beat Australia every individual has to be at their best. That’s the challenge, and that’s how it should be at Test match level. It’s a test of everybody’s credentials.
“But our boys aren’t lacking confidence at all. We understand the quality of the opposition in all the teams in this competition, but we also understand the quality we’ve got within our own group. It was a blip at the weekend, but possibly a timely one – only time will tell.”