Striker Romelu Lukaku and defender Diogo Dalot missed training on Tuesday ahead of Manchester United's Champions League match at Juventus but captain Antonio Valencia and Marouane Fellaini returned.
The match in Turin on Wednesday pits Juve's Cristiano Ronaldo against the team he played for from 2003-09.
Lukaku has been out of form, having failed to score for his club since mid-September, and was dropped to the bench for United's 2-1 home victory against Everton on Oct. 28.
The Belgian, who has scored only four Premier League goals so far this season, missed the trip to Bournemouth last Saturday due to injury.
Right-back Dalot, Fellaini and Valencia have all been absent due to injury but the latter two were part of the main group in Jose Mourinho's training session at Carrington before the travelling squad flew to Turin.
Serie A leaders Juventus are top of Group H on nine points, with United second on four. The Italians won the clash at Old Trafford 1-0 last month.