England took a giant stride toward capturing the Six Nations title by scrapping out a 12-6 victory over Ireland in filthy conditions to become the only team capable of winning the Grand Slam.
In a tetchy match decided by the boot, the unflappable Owen Farrell kicked two penalties in either half to clinch a second straight victory for the English after their 38-18 triumph over Scotland.
"I'm chuffed for Owen Farrell but also the maturity of the whole team," England coach Stuart Lancaster said. "The stakes have always been high but they go even higher with France coming to Twickenham next off the back of a defeat (to Wales) yesterday. That game will be massive."
Ireland hadn't lost a competitive home game against England in 10 years, but a stream of handling errors and first-half injuries to winger Simon Zebo and flyhalf Jonathan Sexton held the team back.
Behind 6-0 at halftime, substitute Ronan O'Gara leveled the score by the 57th with two penalties and Ireland would have sensed victory when England lost James Haskell to the sin-bin.
However, the visitors showed great composure to hold firm and relied on the unforgiving kicking of Farrell - the heir apparent to Jonny Wilkinson - to see the team home.
"If you practice enough it's only another kick. I kick thousands of them," Farrell said. "Conditions out there weren't great but we rolled our sleeves up and got stuck in."
Ireland coach Declan Kidney said Zebo, one of the best players in the 30-22 win over Wales last weekend, would miss the rest of the tournament after breaking a bone in his foot.
"It's been an attritional couple of games and we had a few injuries leading into the tournament, but that's the way it goes," said Kidney, who is already without key forwards Paul O'Connell and Stephen Ferris.
"This championship is a long way from being over. France are in London next time up and England still have to go to Wales. When we get our own game right we will be in a good position. We just were not on the money today."
Aside from its handling errors - nine in the opening 36 minutes - that botched promising attacking positions, Ireland probably wasn't helped by star center Brian O'Driscoll's chaotic build-up to the match. He started despite being with his wife, Amy, for the birth of their baby girl on the morning of the game.
As it turned out, O'Driscoll, like most other backs on the pitch, was hardly seen as conditions invariably turned the match into a battle of attrition.
In Farrell, England has arguably the best kicker in the tournament and he calmly booted long-range penalties in the third and 29th minutes as Ireland was kept scoreless in the first half.
The English became ruffled after the break, though, making a mess of two early lineouts and then getting pulverized at a scrum to allow O'Gara to reduce the deficit to three points in the 45th.
The Irish were given further hope when Haskell was yellow-carded for interfering with the ball illegally at a ruck, and O'Gara kicked the resulting penalty to make it 6-6.
However, England coped well a man light and forced errors that were punished by two penalties from Farrell in a three-minute span to see the match out for arguably the team's biggest away win in Stuart Lancaster's short reign.
"We are suffering a bit in there - it is a tough one to take," Ireland captain Jamie Heaslip said. "England played a smart game in the conditions and played a lot of rugby in our half."
England 12 (Owen Farrell 4 penalties), Ireland 6 (Ronan O'Gara 2 penalties). HT: 6-0.