Fly-half Katy McLean has warned England there can be no more slips if they are to seize Ireland's Six Nations crown.
The title rivals meet at Twickenham on Saturday evening in a key fixture after England's opening-day defeat in France robbed them of the chance to complete the Grand Slam.
Ireland have made good progress through the 2014 Six Nations, thrashing Scotland and beating Wales, and McLean knows they are formidable opposition.
"It was for us massive beating Scotland. Looking back at the France game, we didn't perform well, so the most important thing was getting back on the horse," she said.
"Ireland have a really big pack. They have decent line speed and defence out wide.
"They have some big, hard runners and we know that if we give them the space they will carry well.
"If we're to have any chance of winning the Six Nations, this is a must-win game for us. We'll also have to see what happens with other results elsewhere.
"But we're taking it game by game. We're in a World Cup year so it's about building and making sure our performances go in the right direction.
"We don't want to repeat any of the errors we made against France and we know Ireland will a really tough side who don't want to lose their crown."
Openside flanker Maggie Alphonsi returns to the starting XV as one of seven changes made to the team that dismantled Scotland.