England have received a significant injury boost ahead of their NatWest 6 Nations opener against Italy after a trio of players rated doubtful were passed fit.

Flanker Chris Robshaw (back), lock Maro Itoje (hip) and full-back Mike Brown (blurred vision) have returned to training and have been given the all-clear for Sunday’s Stadio Olimpico showdown.

Of the 34 players summoned to the squad’s Surrey training base, only Zach Mercer has dropped out of contention because of a viral infection.

“We’ve had some miracles. There have been some great recoveries because of the fantastic work from the medical and strength and conditioning staff,” head coach Eddie Jones said.

“All of them (Robshaw, Itoje, Brown) have returned. We did some stuff yesterday (Monday) and they all came through really well.”

Mercer’s challenge at number eight has faded, leaving Sam Simmonds in pole position to start in Rome in the absence of the injured Billy Vunipola and Nathan Hughes.

“Mercer is doing okay but he’s still got a lot of work to do. Physically he’s got a lot of work to do,” Jones said.

“You put him next to James Haskell and you can see the physical work he’s got to do to be a Test player.

“He has other attributes and he’s doing well, but he’s got to get stronger. We play a very physical game and you need physical strength to play it well.”

Itoje returns to the setting for his Test debut two years ago as a superstar of English rugby and one of the squad’s world class operators.

Jones believes the 23-year-old, who has since won 16 caps including three for the British and Irish Lions, has developed into a special player but believes one area of his game can be improved.

“Maro has come on exceptionally well. He’s played for the Lions and been part of a side that drew the series with New Zealand,” Jones said.

“He’s won two Six Nations titles. For a young guy he’s been in successful teams – plus he’s had a lot of club success too.

“His maturity is the thing that impresses me the most. He wants to take more responsibility within the team. He’s been absolutely outstanding.

“He can get a lot better. There’s at least one area of his game that he can significantly improve – his ball-carrying. He’s working on that pretty hard.

“He can be a much more effective attacker and he’s working on that at the moment with (forwards coach) Steve Borthwick.

“He’s doing some great work with him and he’s certainly moving in the right direction.”