Keith Wood will be out of action for club side Harlequins until the end of the month after suffering what is believed to be a minor ligament tear in his shoulder.
The Ireland captain sustained the injury having come on as a replacement for the final 20 minutes in a league match against Leeds last month, his first competitive action since last September.
The hooker is to have a scope on his shoulder to clean up the problem and will miss this weekend's match against Bristol. However, Harlequins team management are confident he will fit for the visit of champions Leicester to the Stoop on January 25th.
Ireland's Six Nations programme kicks off in Edinburgh on February 16th and, barring any setbacks, the skipper is expected to be fit for selection.
Elsewhere, London Irish captain Ryan Strudwick faces up to three months on the sidelines after he tore ankle ligaments on Sunday. Strudwick was hurt during the Exiles comprehensive 20-0 league win on Sunday.
Although initial fears that the 29-year-old might have broken his ankle were dismissed following X-rays, a further scan has revealed the torn ligaments.