Benitez said: "It is not the best situation to come back and play a league game within two days. We will have to use all the squad if it is possible.
"We have tried something different. We stayed for one more night in Sofia rather than flying straight back to Liverpool after the game.
"Maybe it will give the players more time to relax and to recuperate from the match. We will see, only after the Middlesbrough game will we know whether it was a successful idea."