England will be without two scrum-halves for Sunday’s autumn opener against Australia at Allianz Stadium after Alex Mitchell and Archie McParland were ruled out of contention for the visit of the Wallabies.

The disruption at half-back does not stop there, with first-choice fly-half Fin Smith in a race against time to recover from a calf strain in time for the match.

Mitchell damaged his hamstring while on Northampton duty against Gloucester on Saturday. He is to undergo a scan, and his involvement in the second phase of the Nations Championship is in doubt.

McParland missed the 28-14 victory at Franklin’s Gardens because of a calf issue and has not recovered in time for this weekend’s match.

The injury was sustained during England’s training camp last week, and it is hoped he will recover in time to face Japan or New Zealand later in the month.

Head coach Steve Borthwick has called up Ben Spencer and Harry Randall to fill the vacancies created in his 36-man squad.