Centres give Lancaster a nervous wait

England boss Stuart Lancaster will discover on Tuesday whether he must rebuild his RBS 6 Nations backline.

Brad Barritt, Luther Burrell and Kyle Eastmond will have injuries examined in detail to determine whether any of the centres can face Wales in Cardiff next Friday.

England convened their Six Nations training squad at Pennyhill Park on Monday night, with Billy Twelvetrees and Jonathan Joseph the only fit centres.

Concussed centre Burrell could return to training on Friday, while Barritt and Owen Farrell need more tests on knee injuries and Eastmond requires further assessment on shoulder trouble.

England have already left Manu Tuilagi out of their Six Nations training squad altogether as the talisman centre continues to battle groin problems.

Lancaster could almost find his backline for the Millennium Stadium clash on Friday week picks itself at this rate.

"It's too early to give any definitive news on their status," said Lancaster of Barritt, Burrell, Farrell and Eastmond.

England will already contest the Six Nations without Ben Morgan, recovering from a broken leg, and will start the tournament without lock trio Courtney Lawes, Joe Launchbury and Geoff Parling.

Parling's knee injury suffered at Ulster on Saturday led Lancaster to add Northampton lock Christian Day to his training squad.

British and Irish Lions flanker Tom Croft also stepped up from the second-string Saxons, with Tom Wood struggling with ankle trouble.

The 29-year-old has not featured for England since the 30-3 Six Nations loss in Wales in 2013 due to serious neck and knee injuries.

England's sudden shortcomings in midfield could yet lead Lancaster to call on more of the Saxons squad set to face the Irish Wolfhounds in Cork on Friday night.

Rugby league convert Sam Burgess is in line to start in Ireland this weekend - but any more injuries and the Bath star may be promoted by default.

Saxons head coach Jon Callard believes Burgess has all the hallmarks of Test class, but urged caution in expecting the 26-year-old to excel overnight.

"Sam is certainly more than capable, his performance against Wasps at The Rec suggests he's more than capable of playing international rugby," said Callard.

"We'll know probably a little more after Friday night.

"I would have thought if I was a betting man, the seniors would want him to start (against the Irish Wolfhounds).

"The challenge for us is to get the best out of him, and all the other players as well.

"We've got to give them that opportunity to show what they can do.

"I think Bath have handled him beautifully: they've given him the experience, slowly put him into a European Cup situation, and given him that.

"And this is the next stage of his development.

"We're all excited for Sam, but we're just taking it very, very calmly.

"He's still potentially got three World Cups in him.

"So I think there's still plenty of time."