Jamie Roberts admits Wales cannot afford a repeat of their first-half struggle against Scotland if they are to have any chance of toppling RBS Six Nations title favourites France.
The unbeaten Les Bleus are next up for Roberts and company in 11 days' time.
Wales' dramatic 31-24 victory over Scotland kept alive hopes of Six Nations silverware for a second time in three seasons.
But they only prevailed after an astounding finale that produced 17 unanswered points during injury-time. Worryingly for Wales, they leaked two more tries, making it nine conceded in the last three Tests, and France will not require a second invitation to take advantage of such generosity.
"If we play like we did in the first half against Scotland there will be no coming back," said Wales centre Roberts.
Roberts' midfield colleague James Hook expects Shaun Edwards to make a no-holds-barred case for the defence before Wales take on France.
"We are all disappointed with our defence. It is something we are going to be working on in the next two weeks," said Hook.
For now though, Wales will enjoy a win that has kick-started a campaign that began in such disappointing fashion at Twickenham seven days earlier.