Wales’ unconvincing 17-13 victory over Samoa - their smallest winning margin against the South Sea Islanders - did not bode well for remaining Millennium Stadium appointments with Argentina and Australia later this month.

The Pumas, arguably world rugby’s most destructive scrummagers, have beaten Wales four times in their last six meetings and rumble into Cardiff next weekend.

And although Wales head coach Warren Gatland is likely to recall the likes of fly-half Stephen Jones, hooker Matthew Rees and flanker Martyn Williams - all rested after the 19-12 defeat against New Zealand - another testing afternoon awaits.

“We know we have to up our performance,” said giant Newport Gwent Dragons lock Charteris.

“It was a bit like the New Zealand game last weekend in that we played some sustained rugby, then made a couple of errors, lost some momentum and went back the other way.

“Until we can cut that out of our game, it’s always going to be close. We are never going to pull away from sides, and we know another big test is coming next weekend.”

Wales flattered to deceive, cruising into an early eight-point lead and then ending the game in grave danger of losing it.

Samoa centre Seilala Mapusua’s interception try set alarm bells ringing and, had the visitors shown more composure in attack, then Wales would probably have been sunk.

“We will learn from our mistakes,” added Charteris. “The positives are that if we can keep the ball and keep playing the phases, then we are going to challenge and push any team in the world.

“Samoa are full of top-class performers, and they showed it. I took a few big hits, but that is what you expect from professional rugby these days. That’s the way it goes, and you have got to get used to taking a few hits.

“At 17-6 up, we were putting a lot of phases together, but we just could not pull away. They never gave up and put us under a bit of pressure at the end, although we dug in and defended well.”

Not counting the summer tour to North America, Wales have averaged less than one try per Test since their opening victory of last season’s RBS 6 Nations campaign against Scotland.

And they have only scored two in their last four home games, both by Cardiff Blues wing Leigh Halfpenny.