Ronaldo requested to leave Old Trafford and was granted compassionate leave due to a family matter, but he has yet to come back for preseason.
Two weeks from Sunday, when United host Brighton to open the new season, Ten Hag will be concentrating on the players he has available.
‘Of course. But concerning is maybe not the right word. I focus on the players who are there, they are doing really well, and they are in good shape.
‘I prefer to focus on that and develop that. I cannot wait for him to come in, then we will integrate him.’
Anthony Martial has already been told he is staying and is set to lead the line in Ronaldo’s absence after impressing on the club’s tour of Thailand and Australia with three goals in three games.
The Frenchman has combined well with Jadon Sancho, Bruno Fernandes, and Marcus Rashford in the wins over Liverpool, Melbourne, and Crystal Palace.
‘You see they connect really well together,’ added Ten Hag.
‘I think when you see that you are lucky as a manager, the team is lucky. We have a threat, we have weapons, and we have to improve that every day, to develop that.’