Andrew Robertson said both he and fellow left-back Kieran Tierney were played out of position in Scotland's loss to Israel.
Alex McLeish's side were ahead but fell to a 2-1 Nations League defeat on Thursday, with John Souttar sent off.
The Scotland boss opted for a 3-5-2 formation, leaving no room for an orthodox left full-back.
Liverpool's Robertson played in a wing-back role and Tierney, who scored a decisive own goal, featured on the left side of the back three.
FULL TIME | Israel 2 - 1 ScotlandCharlie Mulgrew gave Scotland a half time lead but two second half Israel goals and a John Souttar red card saw Scotland come away with a disappointing loss. October 11, 2018
"Both of us are out of position," captain Robertson told BBC Scotland.
"So it's two positions we need to try and learn. We've played there before but we need to learn it in this system. Unfortunately, that will take time.
"Both of us want to play left-back and there isn't that slot just now.
"The gaffer has looked at it and wants to get me and KT down the left. I've got to start a lot higher and I don't have a winger to play with. From that point of view, it is a lot harder.
"I won't speak for Kieran, but I wasn't good enough."
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