Who are England's number eight options after Ben Morgan injury?

Stuart Lancaster's England beat Samoa and Australia in the final two autumn internationals

With Ben Morgan ruled out of the England squad for the Six Nations which kicks off in four weeks, who are coach Stuart Lancaster's options to replace him at the back of the scrum?

Gloucester number eight Morgan was England's first choice during the final two autumn Tests, but his chances of playing in the Six Nations ended when he fractured his left leg in the 24-23 win over Saracens on Friday.

Former England captain Lawrence Dallaglio says Morgan could return in time for the World Cup in September, but who is likely to be summoned for Six Nations duty.

Billy Vunipola

Vunipola has won 10 caps for England

Morgan has been jousting with Billy Vunipola for the starting eight jersey for the past year, and the 22-year-old from Saracens is now set to return to the England back row for the Six Nations opener against Wales in Cardiff on 6 February.

At his best Vunipola is a high-quality ball-carrier with a huge presence, and he has shown signs of returning to top form for his club in recent weeks after a difficult November.

However, the England management will still want to see Vunipola put in a performance for the full 80 minutes, which is where the best number eights in world rugby - such as New Zealand's Kieran Read - stand apart.

Thomas Waldrom

Waldrom spent four seasons at Leicester before joining Exeter

Thomas Waldrom, the New Zealand-born 31-year-old, won five caps under Lancaster in 2012 and 2013, but slipped off the radar before a summer move to Exeter revitalised his career.

His form for the Chiefs has been remarkable and, with nine Premiership tries, he tops this season's chart, ahead of Christian Wade and Niki Goneva.

Waldrom was drafted into England's squad for the November internationals, but missed out on a place in the match-day squad, with the versatile James Haskell providing cover across the back row against Australia. Waldrom's club-mate Dave Ewers is also in the mix.

Nick Easter

Easter played in the 2007 and 2011 World Cups

There are also two candidates to ponder from left field.

One is the 36-year-old Nick Easter, who continues to excel for Harlequins despite being surplus to requirements throughout Lancaster's regime.

Easter was again influential in Saturday's win over Leicester, with one offload described by Quins boss Conor O'Shea as "out of this world".

Steffon Armitage

Armitage joined Toulon in 2011

Lancaster has always chosen his words carefully when it comes to Toulon's Steffon Armitage, who has been unavailable for England selection while based in France.

However, the door is being left open for the England management to activate the "exceptional circumstances" clause ahead of the World Cup.

Any long-term injuries in the back row will increase the likelihood of England calling on a player who has been one of the leading figures in European rugby over the past couple of seasons.