The Switzerland international has been deployed as part of a back three twice this term.
Midfielder Xhaka's outings in a deeper role came in the Premier League loss to Southampton - which ended the Gunners' 22-game unbeaten run - and the Carabao Cup defeat to Tottenham.
Those results forced manager Unai Emery to defend the selection and Barnes feels repeating the move would be foolhardy.
“Xhaka is not a centre back," said the ex-England international, speaking exclusively for bookmaker comparison platform BonusCodeBets.co.uk.
"If he plays there against Liverpool, that will give Liverpool a lot of hope because that’s not his position and he’s not particularly quick.
“Arsenal still play quite an attacking open game, which no team wants to do against Liverpool.
"If they do that, Liverpool will give them problems. They don’t change to try and take care of the opposition.
"They work hard all over the field, they close down in front, I don’t think they’ll try to do anything different just because [Pierre-Emerick] Aubameyang is a good player.”
Though Liverpool dominated long periods of the 1-1 draw at The Emirates Stadium in November, Emery's side held their own against the Premier League leaders.
Being bold enough to attack Liverpool will be key to Arsenal's success on Saturday, according to Barnes.
And that could force Jurgen Klopp into fielding an extra midfielder to stifle the visitors.
He added: “Arsenal have defensive frailties but they’re also very good going forward, so Liverpool need that extra hardworking defensive midfield player.
"With [Xherdan] Shaqiri playing well, yes going forward we can expose their frailties at the back, however you also have to give Arsenal credit.
"I would be very surprised if he doesn’t revert back to his tried and tested midfield three.”