England forwards coach John Mitchell believes Billy Vunipola is ready to answer the call if asked to start in Saturday's Six Nations finale in Italy.
Saracens number eight Vunipola has not played since his club's final Gallagher Premiership match against Bath on October 4.
England can lift the Six Nations trophy if they secure a bonus-point win in Rome and other results go their way, with fellow contenders France and leaders Ireland squaring off in Paris.
Mitchell said: "Billy has a huge capacity for work. He's a guy that has regularly played 80 minutes in his Test career.
"It's phenomenal how he's able to keep pushing on to the ball and contribute in the way that he does."
England head coach Eddie Jones has always maintained Vunipola needs to be play regularly to be at his best, but Mitchell suggested the back row could have a big part to play.
"It's just a unique quality that he has," Mitchell added. "You never judge the book by its cover I guess, it's what's inside.
Squad update | @alexmitchell97 is called into the squad following an injury to Willi Heinz ahead of this weekend's match against Italy. More details ⤵️ — England Rugby (@EnglandRugby) October 28, 2020
"He's highly motivated and he's proved that in the past as well."
England are expected to beat Italy handsomely, but both France and Ireland can still win the Championship.
Ireland will triumph if they win in Paris with a bonus point – by scoring four or more tries – while France will claim the crown if they achieve the same feat and better England's result.
It promises to be a thrilling last round of matches, but Mitchell would not be drawn on whether England will start the weekend as favourites.
"Firstly our goal is to win the Six Nations and we'll need to set the tone right form the start," he said. "We'll also need to be at our best.
"We keep that focus and we maintain our intent and if we're very good we'll give ourselves every opportunity."
Mitchell said England had a golden chance to lift the nation during the coronavirus pandemic.
"We've got an opportunity to demonstrate our pride and also the privilege which comes with being back playing for England," he added.
"It's an opportunity for us to put smiles on people's faces during a really tough time and I know it might sound generic because you're probably hearing that from all sportsmen, but that time has arrived for us.
"That's really important to us. Preparation is extremely important but there comes a time when you've got to deliver and make sure you wholeheartedly create a smile and give the country something to look forward to."
Scrum-half Willi Heinz has been ruled out because of an unspecified leg injury, with Alex Mitchell drafted in as a replacement.
Mitchell will compete with Dan Robson for the role of supporting Ben Youngs, who is expected to win his 100th cap in Rome.
