Ireland enter the game against the world champions in the unusual position of being hot favourites after England's disappointing opening to the campaign.
And with Ireland's impressive form in winning two games out of two, few people are betting against them beating England for the second year running.
But the Leicester Tigers back, tipped by many to be the British & Irish Lions full-back in New Zealand, is wary of writing England off, and is expecting a fired up opposition on Sunday.
"There is nothing as dangerous as an England team a little down in the mouth," Murphy told BBC Sport.
"Andy Robinson is a very crafty coach and he is sure to have a few tricks up his sleeve.
"You can be sure that when they come to Dublin they will be fired up and it promises to be a very difficult game for us.
"Don't forget they are still World champions. They are too good a team to capitulate completely.
"They are a good team, and they are very capable of bouncing back, and it could be against us. It's going to be one big battle," Murphy added.