Manu Tuilagi and Marland Yarde have been restored to England's squad ahead of Sunday's RBS 6 Nations clash with Wales.
Tuilagi and Yarde have recovered from the respective pectoral and hip injuries that have prevented them from participating in the championship to date.
However, head coach Stuart Lancaster insists they would have to produce something spectacular in training before the team is announced on Friday to play in the penultimate match of the Six Nations.
"They'd have to go some in the next couple of days, it's fair to say," Lancaster said.
"It's a big ask for Manu to come back having had such a long period out.
"He hasn't had any time with us in camp whatsoever, so Tuesday will be the first training session he's done since the Wales game last year."
Since losing to France on the opening weekend, England have delivered impressive wins against Scotland and Ireland to propel them back into title contention.
Luther Burrell has excelled in Tuilagi's traditional position of outside centre while Jack Nowell's form warrants his ongoing selection on the right wing ahead of Yarde.
Lancaster has called on his side to emulate last year's champions Wales by winning the Six Nations despite losing their first game.
"We need to close the deal and win the tournament. It was the objective at the outset to try to win the tournament," he said.
"We didn't quite achieve what we wanted against France. That put us on the back foot.
"From that point on we've used Wales as motivation, after they lost their first game against Ireland last year but went on to win the title.
"In order to win a championship you have got to win four straight after losing the first. No-one has won a title on three wins.
"If we can get the win on Sunday, it's still within our capability."
Meanwhile, Leigh Halfpenny readily accepts that England full-back Mike Brown (above) has the ability to "hurt" Wales.
Brown has made telling contributions in all three of England's Six Nations games this season, scoring tries against France and Scotland while providing a brilliant assist for Danny Care's blistering touchdown against Ireland nine days ago.
Opposite him in the Wales number 15 shirt at Twickenham, though, will be a player who raised the bar last year as Europe's premier full-back.
Halfpenny was player of the series when the Lions beat Australia and 2013 Six Nations player of the tournament.
"He is a great player," said Halfpenny when asked for his verdict on Brown. "He has been playing very well for a good period of time now.
"He has got a good attacking game, he's quick, he's agile, he is a player that can create something and one that we are going to have to watch.
"If you kick loosely to him, he could hurt you, so that is not something we want to be doing."