A squad of more than 20 players was spotted going through a series of warm-up and stretching exercises ahead of the Premier League clash at Anfield, offering a similar sight to the one that puzzled some fans before the Northampton match in September.
Luke Shaw, who has not featured since the Red Devils' 3-1 defeat to Watford last month because of injury and illness, was part of the group.
But Henrikh Mkhitaryan, Anthony Martial, Memphis Depay, Matteo Darmian and Morgan Schneiderlin were not present when cameramen pictured the players going through their pre-match routine under the watchful eyes of Jose Mourinho.
The United manager said at his press conference that Phil Jones is his only first-team player currently missing through injury.
Mkhitaryan has returned to training following a thigh injury while Martial was on the scoresheet in the 1-1 draw against Stoke at Old Trafford last time out.