Paul Pogba will miss Manchester United's Europa League clash with AZ on Thursday as he requires further treatment to a foot injury.
The France international sustained the problem in the 1-1 draw with Southampton in August and only returned to action in last Wednesday's EFL Cup match with Rochdale.
Pogba then played in Monday's 1-1 Premier League draw with Arsenal at Old Trafford but will not travel with the rest of the United squad to Alkmaar.
"Following a specialist's opinion, Paul Pogba requires a period of further rest and conservative treatment for the foot injury he sustained during the game against Southampton in August. Updates will follow in due course," United said in a statement.
Aaron Wan-Bissaka, Phil Jones and Anthony Martial also remain out of action, as does left-back Luke Shaw, who has not played since the 2-1 home defeat to Crystal Palace in August.
Diogo Dalot and Angel Gomes return after injury lay-offs, while manager Ole Gunnar Solskjaer has also called up Brandon Williams, who made his debut against Rochdale, and James Garner.
There are 10 academy graduates in total in United's 21-man group.
The Red Devils beat Astana 1-0 on matchday one, while AZ, who are third in the Eredivisie, drew 2-2 away to Partizan.