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."
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