Zach Mercer emerging as contender to replace Billy Vunipola for England

Zach Mercer was called up by Eddie Jones for the autumn internationals but was treated as an apprentice player. Simon West/Action Plus via Getty Images

LONDON -- England are preparing to be without Billy Vunipola for the entirety of the 2018 Six Nations with Zach Mercer emerging as a contender to feature in the back-row against Italy.

Vunipola suffered his fourth major injury in just over a year in Saracens' draw with the Ospreys last weekend. Confirmation of Vunipola's broken forearm came without a timeframe, but Jones confirmed on Thursday he does not expect to have the outstanding No.8 available for England's defence of their Six Nations title.

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Jones said he "does not think we'll see" Vunipola during the championship campaign as the England No.8 battles back from yet another injury. The start of his injury-plagued spell began against Argentina in Nov. 2016 when he was forced off with a knee injury and then missed the British & Irish Lions tour of New Zealand due to shoulder surgery. And then in September 2017, Vunipola picked up another knee injury that saw him miss the autumn internationals and after just two appearances back for Saracens, he is now ruled out with his broken forearm.

With Vunipola joining Nathan Hughes on the sidelines, Jones' options at No.8 are depleted and Mercer, the 20-year-old Bath back-row, has been elevated to a potential Test contender having previously featured in the squad in an 'apprentice' role with Marcus Smith.

That status saw Mercer train with England, but on the provision they were unlikely to feature in the matchday squad but his form for Bath this term, coupled with the growing casualty list, has seen him lose the 'apprentice' moniker.

"The situation means he's got a shorter apprenticeship than was first envisaged," Jones said. "He's now fully available for selection, he's done well for Bath, I've been really impressed by his work-rate off the ball.

"There's a certain hardness about his game. He's always been one of those gifted boys but now he's doing the tough things. I've been really impressed and he could certainly get an opportunity during the Six Nations."

Sam Simmonds is another option for England at No.8, having made his Test debut during last year's autumn internationals.

While Mercer and Simmonds will be hopeful of playing against Italy, Manu Tuilagi was left out of England's 35-man squad as he seeks to return to full fitness.

"I'd like to see him get fit," Jones said of Tuilagi. "I think Leicester would like to see him get fit and that's what we're hoping is going to happen. If he does that, then he'll be a chance to get selected.

"I think he's looking sharper every week, he's had a long time off [from] the game and he needs to find that sharpness because when he moves up to international level, the requirement for that sharpness is even stronger.

"So we'll just wait and see, appraise him and watch him carefully. Certainly, his attitude has been first-class so there might be a stage during the Six Nations where we can bring him back in."