England's leading scrum-half has been ruled out of the World Cup, after the RFU confirmed that Jack van Poortvliet needs an operation on the ankle he injured last Saturday against Wales.

As first revealed by Mail Sport last night, the 22-year-old Leicester prodigy has been forced out of the global showpiece in France this autumn, as a result of the damage he suffered in a freak accident at Twickenham. 

Van Poortvliet had to be helped off the pitch in the first half, after what appeared to be a low-level collision with team-mate Ollie Lawrence, which left him in obvious pain on the turf.

Borthwick has lost the services of the young Tiger who was favourite to wear the England No 9 shirt in their World Cup opener against Argentina in Marseille on September 9. 

Having officially announced that Alex Mitchell of Northampton has been called up as cover, the head coach said: ‘It’s really bad luck for Jack, and we send him our very best wishes for a swift and successful recovery.’

Mitchell was involved in the last Six Nations, but was subsequently over-taken in the scrum-half pecking order by Harlequins veteran Danny Care, who was included in the tournament squad of 33 named last week, ahead of the younger contender. 

Now, Mitchell will hope to prove that he can challenge for a match-day role, as someone capable of providing vital tempo and spark in attack.

However, the selection equation is now likely to default to what it was in this position over so many years under Eddie Jones and even before his tenure; Care as the primary alternative to Ben Youngs, who is now almost certain to start against the Pumas. 

England’s most-capped player will be charged with implementing a pragmatic, territorial game-plan, which he has so often proved to be a master of in the past.

Meanwhile, this is a savage disappointment for Van Poortvliet, who must now follow the campaign from across the Channel while he recovers from surgery. 

He demonstrated his Test credentials during the series victory over the Wallabies in Australia last summer, and is sure to be back in the selection mix again once he has regained full fitness.

In the long-term, he will compete for caps with the younger generation of English scrum-halves such as Mitchell, Raffi Quirke and Harry Randall.