Luke Charteris admits Wales must raise their game ahead of Saturday's clash with Argentina.
Warren Gatland's men stuttered to a nervy and hard-fought 17-13 win over Samoa at the Millennium Stadium last Friday.
But the giant 6ft 9ins Newport Gwent Dragons believes his team-mates will have to move to another level in a bid to deliver a morale-boosting victory over the Pumas in Cardiff.
Charteris, 26, said: "The game are certainly getting harder and Argentina will be a bigger test for us but it's good.
"It's another challenge and we know we'll have to up our performance from last week. We will take the positives from the game and we played some good rugby as we did against New Zealand but made too many errors.
"But I'd much rather be here with maybe not such a good performance and a win rather than last week with a performance and a loss.
"The important thing is that we learn from our mistakes. We will look at the tape on Monday and try to improve."
Argentina arrive in the Welsh capital, fresh from a uninspiring yet narrow 16-9 defeat to England at Twickenham.
But Charteris insists the visitors will push the home side to the limit up front, especially in the scrum and line-out. He said: "Argentina are renowned for their scrummaging and I'm sure that will be hammered into us all week.
"We have to step up to meet the challenge because if we don't, we're going to come off second best. It's pretty simple for us. We've got to work hard to get the upper hand."
Charteris hopes to keep his place in the side when Gatland names his side tomorrow (Tues) lunchtime and the 16-cap star says he is enjoying his current partnership with British Lion Alun Wyn Jones.
Charteris said: "He is an unbelievable player and when you play alongside someone like that it lifts your own game to make sure you don't get left behind. If i get another chance to play alongside him again I'll be happy."
As the countdown continues for RWC2015, Tournament Chief Executive Debbie Jevans visited the Millennium Stadium to discuss preparations for the eight matches and reveal the positive news that 100,000 tickets for games at the home of Welsh rugby have sold in the last seven days.
Jason Harries is targeting a first win on the World Series circuit this season with Wales. The series returns to action this weekend in Dubai where Harries is part of a team hoping to build from its efforts in round one in October.
Wales skipper Jevon Groves says his side have addressed a few points from Gold Coast and aim to 'hit the ground running' in the next two rounds of the World Series, kicking off with this weekend in Dubai before heading off to South Africa next week.
Wales Sevens manager Steff Thomas is hopeful his side can build from a quarter-final spot in the opening round of the World Series in Australia when his side take part in the forthcoming double header in Dubai and South Africa.