England coach Stuart Lancaster remained optimistic after his side survived a "massive scare" against Italy at Twickenham on Sunday.
Italy fought back from 15-3 to leave England desperately defending their own try line in the final 10 minutes, meaning the hosts kept their Grand Slam hopes alive going into next weekend's title decider against Wales in Cardiff.
"We're delighted to get the win, but relieved. We will have to improve in some areas for the Wales game," said Lancaster.
"No one's been punching the air - it's a quiet changing room. We thought that with a strong start to the second half we could pull away, but Italy played very well in that last 20.
"We had a few guys off with injuries including Geoff Parling and Joe Launchbury, so we need to get back into the camp and check on everyone's condition and then get the selection right for Wales.
"Our intent to play and our attacking shape was there, as was our desire to defend. That phase of play on 75 minutes [defending our own line] was outstanding.
"We'll take the positives but also the things we need to do better. There was though a lot of good stuff to build on so we're not overly depressed."
Highlighting where England fell short, Lancaster focused on a lack of control in the build-up to Luke McLean's score for the visitors, along with England's failure to finish off their chances.
"Our composure coming out of our own half all lead to a poor delivery, poor kick and poor defence that gave them an easy try," added Lancaster.
"I thought we created plenty of opportunities but didn't finish them. Our execution was missing.
"We expected that performance from Italy. Around [Sergio] Parisse the rest of the team grew and you saw the strides they've made. Gone are the days when Italy are beaten easily and we certainly didn't think it would be easy."
England forwards coach Graham Rowntree expressed the coaching staff's relief at clinching the result, specifically with the key lineout steal from Courtney Lawes with time running out.
"Massive is an understatement," said Rowntree.
"We've come through a massive scare there and credit must go to the lads for coming through that. The word 'lottery' is used often when it comes to scrums and it swung both ways today.
England coach Andy Farrell looked ahead to next weekend's meeting in Cardiff by stating that the young English squad would face one of their biggest challenges so far handling the pressure and emotion of going for a Grand Slam.
"We don't talk about favourites. We've not got six days to make sure our preparations are spot on," said Farrell.
"We've had our moments where we have played well and we are four from four, which isn't a bad place to be in.
"Everything is down to that last game and then form goes out the window. It will be another big step for our boys to go down there and handle the emotion and pressure on the day."
By Ben Coles