The 26-year-old, who recently had his contract at Old Trafford extended until June 2025, has missed Man United's last three matches in all competitions with an unspecified issue.
Wan-Bissaka had been expected to return to the squad against Aston Villa this weekend, with Ten Hag saying last week that he was close to making the game with West Ham United.
However, the right-back was forced to drop out of Thursday's training session with another fitness issue, which will equal more time out of action for the ex-Crystal Palace youngster.
Wan-Bissaka has made 17 appearances for Man United this season, but he was also absent for a long period earlier in the campaign due to a hamstring problem.
«Aaron Wan-Bissaka today was training but then he dropped out, so I don't know in this moment where he is and what is the diagnosis. Hopefully he is not too bad,» Ten Hag told reporters during Thursday's press conference when asked for a fitness update.
Ten Hag also confirmed that Tyrell Malacia and Mason Mount are not yet ready to return, while Anthony Martial is a long-term absentee following a groin operation.
Lisandro Martinez is also set to be missing for at least the next eight weeks due to the knee injury which he suffered in the second half of the 3-0 win over West Ham.
However, Ten Hag has said that he is comfortable with his options at the back, with Harry Maguire and Victor Lindelof both recently recovering from fitness issues.
«We have options, [for] how to deal with that position. We have good centre-halves in our squad. The others are also
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