LONDON England flanker Chris Robshaw could miss the Six Nations after aggravating an existing shoulder problem that could require surgery, his club Harlequins said on Friday.
"Disappointing to start this year with this shoulder injury. Will know the full extent on Monday," the 30-year-old former England captain said on Twitter.
"I'm seeing a specialist and will know more after that. It's all up in the air at the moment and it's hard to know where I stand."
Robshaw suffered the setback at Worcester last weekend.
Coach Eddie Jones faces a number of injury woes ahead of their first Six Nations game against France on Feb 4.
"Chris will see a specialist early next week to determine the best course of action for his recovery; either an extended period of rest and rehabilitation, or an operation," the club said in a statement.
Billy and Mako Vunipola have been sidelined with knee injuries, while Joe Launchbury has a calf problem. James Haskell and George Kruis are doubtful with a foot injury and fractured cheekbone respectively.
Captain Dylan Hartley also faces a fitness test following a six-week suspension.
(Reporting by Pritha Sarkar, editing by Toby Davis)