New signing Leny Yoro will be sidelined for three months due to a foot injury and fellow centre back Will Fish sustained ligament damage in a friendly against Liverpool.
The Dutch manager also expressed uncertainty about the availability of Harry Maguire, Victor Lindelof, and full backs Aaron Wan-Bissaka and Luke Shaw.
"Harry Maguire missed the game (against Liverpool), was a precaution but is still a question mark for Saturday," Ten Hag told reporters.
"So we have training, we have to see whether he is fit enough or not to be available.
"Victor (Lindelof) played but also he’s a question mark and also Azza (Wan-Bissaka) and Luke Shaw are both question marks, we have to assess them tomorrow (Friday)."
Ten Hag noted that Argentine international Lisandro Martinez could be a defensive option but did not specify return dates for players who joined the squad late due to international duty.
"That is (on an) individual basis and every (player) has a different background," he added.
"So from individual to individual we will assess them and make a decision whether they start, come from the bench or they don't play."
Striker Rasmus Hojlund will miss the match due to injury, which opens the door for Joshua Zirkzee to make his United debut less than a month after joining from Italian club Bologna.
United beat champions City 2-1 in the FA Cup final in May with an impressive performance.
"So, we always want to win," Ten Hag said. "It's about a trophy, we will put out a team that is very competitive to win this trophy."