Mako Vunipola admits England will need a vastly improved performance against Wales if they are to win their first Grand Slam since 2003.
England stuttered to an 18-11 victory over Italy at Twickenham on Sunday - with the Azzurri coming dangerously close causing to a major upset.
And although the win means England have given themselves a shot at a Six Nations clean sweep in Cardiff on Saturday, Vunipola conceded that the squad know that their display against the Azzurri was not good enough.
"We all know in the changing room that a repeat of this won't be good enough," said the 22-year-old. "It kind of feels like we lost the game, I think all the boys are disappointed with how we performed.
"We got the win against a quality Italian side but take nothing away from them as they played out their skins, if we perform like that next week we will have no chance."
Vunipola was one of the bright points from the game, with the loosehead prop putting in a solid display in his maiden start for England.
He made his mark from the off as he helped demolish the feared Italian pack in the first scrum, while he also impressed in the loose.
Next up, though, is a potential showdown with Wales tighthead Adam Jones.
"Adam Jones is a great tighthead as he showed on the Lions tour a few years back and is probably No 1 in the northern hemisphere," added Vunipola.
"It is going to be a challenge for us and we are looking forward to it."