Former Ireland head coach Eddie O'Sullivan says Ireland should expect a "bar room brawl" on Saturday against an England side struggling for form.

England beat Wales last time out but struggled for fluency in the 23-19 win.

"We know where we are, but where are they? They are not in a good place," O'Sullivan said.

"I'm not saying it's a bad place, but they are not in a good place.

"England have struggled. In the context of where they're trying to get to and where they are, the gap between them and winning a World Cup is quite large at the moment.

"That's not to say that England don't have the capacity to change things very quickly. But this English team at the moment are struggling a bit," the ex-Ireland coach told BBC Radio Ulster's Sportsound Extra Time.

Ireland produced a impressive display to beat England in Dublin the last time the sides met 12 months ago.

Before that, England had enjoyed the upper hand of the rivalry with four straight wins delivered in emphatic fashion, with their pack physically dominating their Irish counterparts.

"They need to get a result on Saturday. If they win on Saturday and then lose in Paris things aren't going to be so bad, but if they lose their last two Six Nations games it will be very difficult," O'Sullivan said of England, who will take on France on the final day of the tournament.

"They need a result and the way they can get it and for that reason they are very dangerous. They're a team that has to win.

"If we lose at Twickenham it won't be the end of the world, we'll be disappointed but I think their stakes are higher.

"This will be a bar room brawl and we need to be ready for it. If we get to play on the weekend like we know we can play we'll beat them, there's no question.

"But they have to stop us, and that could be very physical."

'Henderson return could bolster back five'

Ireland will travel to Twickenham without Andrew Porter, after the loosehead prop sustained a tournament-ending ankle injury against Italy.

It is likely that either Test centurion Cian Healy or Munster's Dave Kilcoyne will replace Porter in the front row, with the return of British and Irish Lion Iain Henderson giving Andy Farrell food for thought in his second row selection.

An adductor injury saw vice captain James Ryan miss the Italy win, when Ryan Baird started alongside Tadhg Beirne at lock.

"This is going to be a hugely physical competition. Ireland's back five are a little bit light compared to England's and I think he could bring Henderson in to bolster the back five," said O'Sullivan.

"Someone with that experience, that bulk and physicality. Then what does he do with Tadhg Beirne who has been outstanding?

"Do he disrupt the back row that we have at the moment? There's risks along the way but they're good risks in that he's making informed decisions.

"With Porter being out I think Cian Healy will be fine, but if it's a very physical game and a very fast game how long you'll get out of Healy I don't know.

"That front row of Porter and Furlong together has always been really the basis of our big performances."