PAT Sanderson's back problem is likely to keep him out of the Warriors side for the whole of January.
The Worcester skipper missed the Boxing Day defeat at home to Bath after picking up the injury in the previous week's European Challenge Cup match against Connacht.
He is expected to return to fitness in four to five weeks, which would rule him out of Worcester's Premiership matches with Newcastle and Northampton as well as their final two Challenge Cup matches.
It is a big blow for Sanderson who now faces a race against time to be fit for England's Six Nations campaign.
The back-row star made a big impression on the England coaching staff during the autumn internationals and looked set to feature in the Six Nations opener against Wales at Twickenham on February 4.
Another England ace, fly-half Jonny Wilkinson, has been named in Newcastle's 27-man squad for the match with Worcester on New Year's Day.
Wilkinson could make a return to action at Kingston Park following surgery on his troublesome groin.
Falcons' director of rugby Rob Andrew will decide after today's training session whether or not to name the British Lions star in his starting line-up.
He said: "Our policy with Jonny, or any other injured player for that matter, has never changed.
"If he is fit then he will be considered for selection. If not, then we will keep going with his rehab until he is fully ready."
Worcester are desperate to register a win after losing their unbeaten home record against Bath in an 18-36 loss.
Director of rugby John Brain said: "I think it's always hard when you lose but we aim to bounce back. We've got a long trip on New Year's Eve, we're playing New Year's Day and we want to make it a worthwhile trip."
And Brain's side have been paid a compliment by Falcons' prop Micky Ward, who rates the Warriors pack among the best in the business.
He said: "Worcester are probably up there with Saracens as the best pack in the league and I love playing against teams like that because you can test yourself against the best there is in this country."
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