Manu Tuilagi must prove his fitness and intensity in training on Tuesday if he is to break back into the England side for their crucial Six Nations clash against Ireland this weekend.
Tuilagi has been declared fit for Sunday's clash in Dublin having recovered from an ankle injury.
But following impressive displays from Billy Twelvetrees and Brad Barritt in England's 38-18 defeat of Scotland on Saturday, Tuilagi faces a fight to break back into Stuart Lancaster's starting XV.
Lancaster will make his decision following a decisive double training session at their Surrey headquarters on Tuesday and skills coach Mike Catt says it will be a close call.
"It is always difficult but it is a great headache to have," said Catt.
"From a team point of view you have three guys and each of them bring special attributes. It is great Billy has come along and performed the way he did against Scotland on his debut.
"Manu has been out of the game for three or four weeks. We will see how they all train and we will go accordingly from there.
"If the guys have performed exceptionally well on the weekend, the guys coming in need to make sure they have the tempo and up the intensity to really put their hands forward. That is what we want on Tuesday."
Whoever plays in midfield for England, they will face a formidable challenge with Ireland trio Jonathan Sexton, Gordon D'Arcy - who is currently struggling with a dead leg - and Brian O'Driscoll hitting top form.
O'Driscoll in particular shone in Ireland's 30-22 victory over Wales on Saturday and Catt admits the Ireland star will need special attention.
"It would be very hard (taking him out of the equation)," Catt said. "O'Driscoll is playing exceptionally well at the moment. I thought that first half Ireland produced (against Wales) was exceptional. We know they are capable of doing that.
"Defence is across the board. Everybody knows their roles.
"We need to focus on our attacking game too, which went pretty well against the Scots, and try and starve them of the ball so they can't do what they are good at.
"It is a little game of chess we have to try and win."
England have not yet officially ruled out Ben Morgan from their Dublin plans after the Gloucester No8 sprained his ankle early in the second half against Scotland.
But Morgan's chances look bleak. He was wearing a protective boot and walking at the England hotel with the aid of crutches.
James Haskell is set to start in Morgan's anticipated absence with Tom Wood shifting across the back row from blindside flanker to No8.
The Wasps No8 Billy Vunipola has returned to training and he would offer England a powerful and dynamic option off the bench.
"Billy Vunipola trained with us this morning and he is doing the afternoon session. I am looking forward to seeing what he can bring," Catt said.
Who will win between England and Ireland?