Sancho and Rashford were part of a free-flowing front three along with Anthony Elanga, but Ten Hag believes Ronaldo can be incorporated into his system.
"I think he can," said the United manager, who brought Ronaldo on as a substitute in the 86th minute. "The whole of his career under several managers he did, several styles and systems. He always performed, so why can't he do this?
"His age is not an issue. If you are good enough and you're old and you still deliver performances, you are also good enough."
"We have a squad and a way of play, of style, but also a game plan," Ten Hag said when asked about the reasons behind his team selection. "You look at what's the best approach for the game. We need a squad because we have many games to cover so we make a team out of the squad, we stick together as a squad and we achieve a lot. I'm confident about that."
Ten Hag is set to have new signing Casemiro available when he takes his team to Southampton on Saturday. The Brazil midfielder watched from the stands after being unveiled on the pitch ahead of kickoff against Liverpool and is in line to make his debut at St Mary's.
"He has won so many trophies in his career," Ten Hag said. "He knows the road, how you win games and how you win trophies. We have more players who have already won trophies in their career.
"That has to be a guidance for the rest of the team, so they know and understand how to win things."