Ten Hag was sacked as Man United manager on Monday, with Van Nistelrooy placed in charge on an interim basis, and he guided the team to a 5-2 success over Leicester City in the last-16 stage of the EFL Cup on Wednesday night.
Ruben Amorim is set to arrive from Sporting Lisbon as the new manager, with a deal expected to be confirmed in the near future, although he is likely to remain in his current role until the November international break.
As a result, Van Nistelrooy could have three more games at the helm against Chelsea, PAOK and Leicester City.
The Dutchman expressed a desire to remain at Man United after the EFL Cup win over Leicester, and he has now hinted that he is fully expecting to stay as assistant manager once the new head coach has arrived.
Van Nistelrooy is set to lead Man United against Chelsea
"I'm guessing that too, so yes," Van Nistelrooy told reporters when asked whether he would lead the team against Chelsea. "It's going to be a short job as an interim, that was communicated very clear and I was happy with that.
"I felt I was called upon to help the club forward in this situation. Obviously, it was difficult that Erik had to leave, I was very disappointed, obviously with very mixed feelings about that but you have to switch the mindset to win because 75,000 people are waiting and celebrating and millions are watching at home. That's what we tried to do, same for Sunday and then we'll see.
"I decided to come back here for a very important reason that I'm here. I came as an assistant to help the club forward and I'm still very motivated to do so in any capacity. As an assistant, and now as an interim manager, and after that I go back to my assistant contract that I have here for this season and next.
"I'm very motivated to stay here and help the club forward, that's my absolute goal."
Van Nistelrooy opens up on Ten Hag conversation ahead of Leicester game
Van Nistelrooy also revealed that he spoke with Ten Hag ahead of the Leicester match and said that his fellow Dutchman was "hurt he had to leave".
"I saw him on Monday and spoke to him before the (Leicester) game. He was disappointed and touched because he really cared for the club. That's why he's also hurt that he had to leave but also proud of his achievement here winning the two cups," he said.
When questioned on Amorim, Van Nistelrooy said: "Is he already announced? So we don't know. Again, what the future will bring, we will see."
Man United will be bidding to return to winning ways in the Premier League when they host Chelsea on Sunday afternoon, and the fixture is the second of four straight home games for the 20-time English champions.