England out-half Marcus Smith is awaiting scan results on a leg injury sustained in training just five days before the Guinness Six Nations' opener against Italy.
Steve Borthwick’s squad are on a training camp in Girona and the England head coach is scheduled to announce his starting line-up on Thursday.
Owen Farrell had already made himself unavailable for this season’s Six Nations in order to focus on his mental well-being and Smith was a leading contender to fill his boots.
Smith left England’s training camp on crutches and headed for a scan after his session had been cut short.
England attack coach Richard Wigglesworth told several national media outlets: "Hopefully it’s very precautionary, but if he is not (available) it would definitely be a blow for us.
"It wasn’t a big incident. He was just jogging, but he pulled up and happened to be right next to a physio by the sideline, so they walked off after that. All the usual stuff (medical assessments) will happen."
Elsewhere, Javan Sebastian and Ross Thompson (above) have been added to the Scotland squad ahead of Saturday's Six Nations opener away to Wales.
Edinburgh prop Sebastian was not included in the initial 39-man pool, named earlier this month, as he battled to recover from a knee injury sustained in December.
However, the 29-year-old – who went to the World Cup with Scotland – has now been deemed fit enough to be enlisted for duty after his fellow tighthead and clubmate WP Nel withdrew with a neck strain.
Glasgow stand-off Thompson has also been called up to compete with Finn Russell and former Munster back Ben Healy for the number 10 jersey after Adam Hastings dropped out through injury last week.
Warriors pair Euan Ferrie and Jamie Dobie are not officially part of the squad but are currently training with the players in Spain as they step up preparations for Saturday’s showdown with Wales in Cardiff.
Listen to the RTÉ Rugby podcast on Apple Podcasts, Spotify or wherever you get your podcasts.
Follow a live blog on France v Ireland in the Guinness Six Nations on Friday from 7.30pm on rte.ie/sport and the RTÉ News app and listen to live commentary on RTÉ Radio 1
Watch live coverage of Ireland v Wales (24 February) and England v Ireland (9 March) on RTÉ2 and RTÉ Player.
