Eddie Jones revealed Ben Youngs is unlikely to be fit to face Wales next weekend after sustaining what appeared to be a serious knee injury early in England's Six Nations win over Italy.
Youngs was carted off less than 10 minutes into a resounding 46-15 win for the defending champion in its first game of the tournament at Stadio Olimpico.
The scrum-half was distributing the ball from the base of a ruck when he was tackled by an opposing player and went down in agony.
England coach Jones does not expect the playmaker to face Warren Gatland's side at Twickenham and said he will undergo tests.
"He'll get an examination tomorrow. But he's unlikely to be available for the Wales game," said Jones. "I'm always optimistic. It's a knee injury, it looks like a ligament."
Anthony Watson and Six Nations debutant Sam Simmonds scored two tries apiece, while Owen Farrell, George Ford and Jack Nowell also crossed for England.
Scores from Tommaso Benvenuti and Mattia Bellini had kept the Azzurri in it, but England added three tries in the last 13 minutes to run away with it.
Italy coach Conor O'Shea said: "I'm proud and angry. I'm proud because I think we saw a team that has a lot of potential out there for the future and played some really good rugby against a great side. We were up against the number two side in the world and we caused them a lot of problems.
"I hate sitting here because we've lost and it's another statistic but in terms of where this team can go and what we were creating, it's another step forward."