Leigh Halfpenny says no player can take their place in Wales' World Cup squad for granted.
Fellow British and Irish Lions Richard Hibbard, James Hook and Mike Phillips were among eight dropped players as coach Warren Gatland trimmed his squad to 38 players last week.
Halfpenny, 26, says players must prove they deserve to go to the World Cup.
"You can never take for granted that you're going to be in the squad," said the full-back.
"You have to be working as hard as you can in training and showing the coaches how much you want to be in that squad and earn the right to be in the squad for the World Cup."
"The commitment that has gone in from every player has been fantastic and everyone is pushing each other for a place in the squad."
The Toulon star said it was "hugely disappointing" for the omitted players.
He added: "You feel hugely disappointed for the boys."
Will Greenwood, a 2003 World Cup winner with England, believes Wales will not reach the last eight of the the 2015 tournament, with Gatland's men drawn in Pool A with England and Australia.
Wales were beaten by France in the 2011 World Cup semi-finals and went on to lose to the Wallabies in the third-place play-off.
"Our goal is to go one step further, make that final and hopefully lift that trophy," said the former Cardiff Blues player.
Hosts England kick off the tournament against Fiji on Friday, 18 September.
Wales' challenge begins in Cardiff on Sunday 20 September against Uruguay.