Chelsea boss Benitez sees midfield as Luiz's long-term position
Benitez confirmed he will definitely return to midfield once John Terry shakes off his knee injury.
The Brazilian played there in last week's Club World Cup semi-final win over Mexican's Monterrey.
And Benitez said: "I played him as midfielder and didn't want to do it again for the final because it would have been too demanding for him because he's a centre-back.
"We knew it was too demanding and thought he would not have the same fresh legs.
"But midfield is easier for him. At centre-back one mistake and everyone sees it.
"In midfield, it's easier. He likes to play and enjoys going forward. I encourage him to try things.
"I'd be worried if a player is not trying things in the final third - and he likes to take risks where necessary."