Saints star Courtney Lawes has added a stone of muscle to his frame in time to spearhead England's assault on Ireland generals Johnny Sexton and Conor Murray.
Lawes has been battling a bulging disc in his back that initially became troublesome in September, ruling him out of the autumn opener against South Africa and then until recently affected his club form for Saints.
The injury also prevented him from doing the gym work needed to enhance his athletic build, but he has since been restored to his target weight of 18.1stones through weights sessions and binge eating.
Charlie Hodgson, Jules Plisson and Morgan Parra are half-backs who have felt the full force of Lawes' bone-crunching tackles and his defensive expertise will be needed in Dublin on Saturday.
Sexton and Murray are vital components in Ireland's carefully-crafted gameplan but by placing them under pressure, England have a chance of causing an upset in their Guinness Six Nations opener.
"After my back injury I've managed get my weight back on again and I'm feeling strong so I'm ready to go," Lawes said.
"If I get the opportunity I'll look forward to getting out there and putting in some tackles!
"Any weight that I can put on is only going to help me. I struggle to put size on and my fat never goes up regardless of what I eat.
"It's not ideal when you want to be 117kg and you can't get past 115kg. It's just genetics. A bit bigger would be great, but I can work at my weight of 115kg.
"As soon as I start running my weight just falls off. I can't put on size unless I do a load of weights and eat a load of stuff.
"You get an opportunity to do that in England camp so hopefully I'll put on a bit more, but I'm around the right weight now.
"I just eat whatever. It doesn't really matter what it is. We do meal counts in terms of your fat percentage and mine never go up, no matter what I eat, so I just pile into whatever I can.
"I try to eat as many calories as I can. I don't count the calories, I just shovel food down my throat! I've put on just over a stone since the autumn.
"I couldn't do weights for six weeks because of my back and it wasn't good - I'd got pretty thin.'
"I certainly feel the difference in terms of hitting and being able to get through contact a bit easier. Now I feel that I can take on that role of stopping people."
Lawes is an option for the second and back rows and could be selected at blindside flanker if Brad Shields fails to recover from a side strain with Mark Wilson also an option in the position.
"I'm not the kind of person who randomly takes someone out. It's fine lines," Lawes said.
"But if I am trying to get to the half-back before he passes and my head goes down before he has passed, then I am going to make the shot regardless of what the ref says.
"But I'm not going to be taking any risks at the weekend, for sure. I'm going to stay in the system.
"My first priority is getting our forward pack on the front foot. After that is when Sexton comes into the game."