James Hook reckons Wales need at least one victory over the southern hemisphere sides next month to confirm their World Cup ambitions.
Wales will host Australia, South Africa and New Zealand, plus their 2007 World Cup conquerors Fiji, at the Millennium Stadium in the autumn internationals.
Since Warren Gatland was appointed Wales coach before the 2008 Six Nations campaign, his side have played the Tri-Nations sides nine times, but recorded just a solitary victory against Australia two years ago.
Ospreys star Hook said: "We've got to try to beat one of these big teams - we want to win them all, obviously, but we need to win at least one or two to put us in good stead for the Six Nations and then on to the World Cup next year.
"If you look at the games, we are not far away. It's a silly penalty, a silly mistake now and again that has cost us.
"We just need to believe in ourselves. We know we can beat these teams, and we've got to believe from the start.
"These are massive games for us. We want to try to get a big scalp and get something out of these autumn internationals."
Hook may be asked to start at full-back in Wales' opener against the Wallabies on November 6, after Lee Byrne broke his hand on Magners League duty for the Ospreys against Glasgow.
Gatland is also set to assess the merits of full-back alternatives like Leigh Halfpenny, Tom Prydie, Chris Czekaj and Will Harries.
Hook - whose preferred position is stand-off - added: "It is a possibility with Lee being out. It is the same sort of situation as last year.
"We've got two weeks of training before the first game against Australia. This time last year, I didn't have much experience of full-back, so I was thrown in at the deep end a little bit. But I've got that much more experience of full-back now, if I am called upon.
"At the end of the day, I look back a couple of years ago when I was on the bench for most of the Six Nations and the autumn Tests - that's a lot more frustrating.
"As long as I am playing, I am happy, whether it's centre, outside-half or full-back."