United have won five out of their seven games in 2023 and are fourth in the Premier League standings on 39 points.
They have also reached the semi-finals of the League Cup and the Europa League's knockout stage, and are favourites to beat Reading in their FA Cup fourth round clash on Saturday.
"Football is not decided on paper. We have to be ready for every game. Every opponent will be tough, especially in the FA Cup. For them it is a perfect chance. We have to be on the front foot and fully focussed," Ten Hag told reporters.
"We want to win every game. We play every game fully. The next one is always the most important.
"We always have selection issues, but I think tomorrow we will have a strong selection for this game, we have a good squad, we can cover things."
United will play nine times between January 28 and February 26, starting with the FA Cup game against Reading before taking on Nottingham Forest in the second leg of a League Cup semi-final and facing Barcelona twice in the Europa League.
Ten Hag said he was happy with the depth of his squad, and when asked if fringe players like Facundo Pellistri (21) could go out on loan, the Dutchman said, "some players we are open for loans and some we are not because they have to develop in our environment.
"We put on Pellistri (in a first-leg semi-final win over Forest on Wednesday), that is a signal.
"Brandon Williams (22) was in the selection for Wednesday. He is part of it. It is also up to him. I like him. We have to work with him and see where his developments can go. It's up to him to see when he takes his chance. If he wants a loan, we have to talk about that."
Winger Jadon Sancho (22) returned to team training earlier this month for the first time since October, but Ten Hag did not mention if he would feature in Saturday's game.
"He is training with the team, and we will see, so he's improving, he's making steps, and we will make the decision after training," Ten Hag said.
"I said he's on the way back, he's making steps, he's back in team training, and we have to see when he's ready to go back into games."
Ten Hag added that Diogo Dalot (23) "is definitely out" for the game and said Luke Shaw's (21) availability is also in doubt.
