Wales wing George North has been warned about his form before Friday's Six Nations match against Ireland.
Defence coach Shaun Edwards highlighted the right wing, where North played in the defeat by Scotland, as an area of recent defensive weakness for Wales.
After successive losses to Scotland and England, Wales name their team to face Ireland on Wednesday.
"If he is selected, I expect George to certainly be on his mettle," said Edwards.
"I also think that George had a very good game against Italy, in very, very difficult circumstances. He got a really bad bang on his leg and toughed it out well.
"Yes he wasn't at his best against Scotland but I think great players, who've done great things for you in the past, sometimes deserve a warning."
North started the Six Nations campaign in fine fashion, scoring a spectacular solo try in Wales' opening win in Italy.
Injury ruled the 24-year-old out of the next game against England, which Wales lost thanks to a late try from England's left wing Elliot Daly, who evaded a tackle from North's replacement, Alex Cuthbert.
North returned for the defeat by Scotland, in which Wales conceded a try on each flank.Flats and Shanks go in search for Wales' lost mojo
Edwards suggested the right wing, where North was defending for Scotland's second try scored by Tim Visser, was a source of concern for Wales.
"When it comes to conceding tries, we've conceded tries on our edge, usually our right edge [Elliot Daly for England and Tim Visser for Scotland], one on the left side [Tommy Seymour for Scotland]," Edwards added.
"They were individual mistakes because they didn't do what they practised in the build-up to the game.
"They decided to do what they wanted and not what the rest of their team-mates expected them to do."'I'd like to see Davies start' - Gough
Sam Davies and Wales' 'finishers'
Following Wales' defeats against England and Scotland, there has been a clamour for changes - with several pundits calling for Ospreys fly-half Sam Davies to be given a first international start.
Edwards played down the prospect of experimenting against Ireland in Cardiff.
"Every game, particularly Six Nations' games against Ireland, great rivals of ours, we will be picking our best team to win this game. Obviously World Cup rankings are a part of that as well, but it is a Test match against Ireland so bring it on," he said.
"Sam's been very useful for us. We know he is a very creative player. He is pretty much a regular in the 23 now and he has come off the bench and added a lot of creativity, there is no doubt about that.
"I keep going back to the same thing - sometimes your best players are on the bench because it is all about that last 25 minutes.
"It has been proven time and time again, games are won and lost in the last 20 minutes. What do England call them? Finishers? I like that, it pretty good terminology for what is a 23-man game now."