"Pre-season was a great chance for Axel to show what he's capable of next to our players," Solskjaer said when asked why Tuanzebe was chosen ahead of Jones, Smalling and Rojo.
"I've seen him at Villa, I've seen him in midfield here, and at right-back. But I wanted to see him next to Victor, next to Phil.
"We know he's going to be a big, big part of this club in the future. He probably impressed me more than I expected. That's why he's on the bench. He can slot in midfield and right back as well, so he's able to play different positions."
The manager added: "Axel is knocking on the door, he wants to play. I hope Victor and Harry don't give me a reason to change. No injuries, suspensions or lack of concentration. They can both play, they read the game really well.
"Of course, Harry, with his presence in the box, it's great for any centre-back to have that presence next to them. I'm sure Victor will enjoy that.
"Then again, Rojo, Smalling, Jones, Axel, they all want to be part of that. There's competition for those places."