Manu Tuilagi and Henry Slade are on course to be fit for England's crunch Six Nations showdown with Ireland at Twickenham on Sunday.
Tuilagi suffered a groin injury early in England's defeat to France on the opening weekend of the tournament, while Slade has been out since sustaining an ankle injury in December.
The centres trained with the Rugby World Cup runners-up on Wednesday and could face joint-leaders Ireland this weekend.
England head coach Eddie Jones said: "Manu trained fully so should be in contention for selection. It's good to have a quality player back.
"Slade also trained so we have just got to monitor his progress. He has a positive chance. He's a quality player. This gives us more options."
One player who will play no part is prop Mako Vunipola, who flew to Tonga and is not available for "family reasons".
Jones says England are well stocked to cover for the absence of the British and Irish Lion, with Joe Marler and Ellis Genge vying for a start.
The Australian said: "Mako's a quality player but we are lucky we are blessed with two outstanding loosehead props in Joe and Ellis, so we can recover the loss of Mako.
"But it's disappointing to lose him."
Genge scored the winning try in a battling 13-6 defeat of Scotland before the rest weekend.