Vunipola made his long-awaited return for Saracens during their Premiership victory over Newcastle Falcons on Sunday, ending a three-month spell on the sidelines with a knee injury.
England have already confirmed that the number eight will be involved in the 23-man squad for the match at Twickenham, and pictures from the team's training base in Surrey this afternoon appeared to confirm that he would be restored straight into the starting lineup.
Two whiteboards positioned at the side of the training pitch displayed formations for the session, and Vunipola's name was included at number eight in place of Nathan Hughes.
Victory for England would see them claim the Calcutta Cup and Triple Crown in addition to moving within one match of a second consecutive Grand Slam title.
A win would also equal New Zealand's record of 18 consecutive Test victories and could be enough to wrap up the championship should Wales beat Ireland on Friday.