Solskjaer played the defender in midfield for the 0-0 draw with Europa League opponents Real Sociedad.
And the manager says Tuanzebe could again feature in the new role in the coming week: "It's one of those positions now we suddenly have Scott (McTominay), Donny (van de Beek) and Paul (Pogba) out.
"We've been really well off before and now we might have to look at options because I'm not sure if any will be available [for Chelsea]. Paul's definitely not I don't know about Donny or Scott."
On Fred's substitution, he added: "Fred came off, he had a booking so I didn't want to take a chance with him. It's about getting through the round. 4-0 away from home and we kept another clean sheet. Well done!"