London - Stuart Lancaster admits his England players simply must be more clinical and ruthless against France if they are to capture the Six Nations title at Twickenham.
The head coach was left with mixed emotions after the 25-13 victory over Scotland which was much more of a struggle than it needed to be with the hosts blowing hot and cold in front of the try line.
Jack Nowell's late try, England's third of the game, ensured Lancaster's team jumped to the Six Nations summit. But only just.
They have a superior points difference over Ireland (37 to 33) with Wales third (plus 12).
The scene is now set for a nail-biting, tense and thrilling final day of the Championship next Saturday when Wales kick off the day in Rome, the Irish then play in Edinburgh and the English host France.
England, who will know what they need to do by the time their game kicks off, will start favourites to lift the trophy if only because of home advantage and Wales need a huge win over Italy.
But the Irish will still fancy their chances against a Scotland side yet to win a game in the tournament.
But Lancaster insisted: "We will have to be sharper than we were here to beat France, that's for sure. The French will not let us miss so many attacking opportunities. They will be dangerous and we must be more clinical.
"We have given ourselves a chance thanks to this win and to the Welsh beating Ireland. And it promises to be a very tense and exciting last day. We will know our own destiny come the final game because our one is the late kick off time.
"But we cannot afford to look at what the other two sides have done. We must just concentrate on what we can do and ensure we do the business against France.
"We were delighted here to make so many try scoring chances but disappointed to let so many go by. To convert three line breaks from twelve we made was not what we wanted."
After Wales had beaten Ireland in Cardiff to open up the title race, Jonathan Joseph and George Ford, who amassed 15 points in total, were England's other try scorers at Twickenham.
Centre Mark Bennett grabbed Scotland's only try and they saw a 13-10 half-time lead dissolve into a 25-13 loss.
England wasted a glut of try scoring chances with two forwards pass, ruling out tries for Jonathan Joseph and Mike Brown, plus desperate late tackling from the visitors.
The Calcutta Cup seemed close to slipping through their fingers as their Grand Slam dreams did in Dublin a fortnight earlier. But the men in white managed to compose themselves in the second half and finish the job.
Fly-half Ford admitted: "There was never any panic at all but we should have taken a few more of our chances. We made plenty of line breaks but now we are in with a shout of winning the Six Nations.
"The French will be a very dangerous team and can beat anybody on their day. We are expecting a very hard Test match because they will want to come to Twickenham and silence the crowd straight away.
"I'm not sure what the coaches are planning in terms of watching the other games but we will need to know what we need to do on the pitch come kick off time. First of all we will just want to win a Test match and the Championship.
"It's going to be a huge week again. I always think every week is the biggest of my career."
While the Six Nations title promises to go right down to the wire with plenty of blood, sweat and tears before it is decided on the final day, Scotland are left to try and avoid the wooden spoon and an embarrassing whitewash at home to Ireland.