But they face a daunting task to get out of their pool which contains sevens champions Australia, South Africa and reigning champions New Zealand.
Lewis though is quietly confident his side can pull off a major upset if they are written off byt the Southern Hemisphere teams.
He said: "Going into the World Cup, we're underdogs. If you go online or read any press releases, Wales is always mentioned as the last name in the pool.
"I think people are writing us off in favour of the bigger names. Australia - World Cup winners at 7s, South Africa - because of what their male counterparts do, and world champions New Zealand - they are fantastic.
"So nobody gives us a second thought, that's great, that suits us down to the ground, and that's a good place to be.
"I'm really happy with the squad that we've got. I know it is a cliché but it is a real mixture of youth and experience.
"I think some of the young players who have come in have added some vibrancy and mixed things up a little bit.
"They've certainly shown they deserve their place here and I think there is a good spirit in the squad."
Wales Women's World Cup squad:
Forwards: Jenny Davies, Lowri Harries, Catrin Edwards, Rhian Bowden, Gemma Hallett, Shona Powell-Hughes, Louise Rickard, Rachel Taylor, Catrina Nicholas, Jamie Kift (captain), Sioned Harries, Lisa Newton, Caryl Thomas
Backs: Amy Day, Laura Prosser, Awen Thomas, Naomi Thomas, Mared Evans, Clare Flowers, Ceri Redman, Mellissa Berry (capt), Caryl James, Non Evans, Elinor Snowsill, Elen Evans