Adrian Mutu was in an offside position when the onside 19-year-old Jovetic went through on goal to put La Viola ahead and Benitez was left bemused by his shaky defence and added: "It is the new law -and another mistake by us.
"If a player is in such a position he is offside and it makes it difficult for defenders who are distracted by him but the law says the other player coming from deep is fine, he can go through. Just another error by us."
However, Benitez insisted Reds supporters would see a vast improvement in coming weeks, starting with Sunday's crunch Premier League tie against Chelsea.
"We now have Chelsea away at the weekend in an important Premier League game," he said. "I believe you will see a different Liverpool in that match, a totally different performance with a different mentality.
"Then we have Lyon home and away in this group, they are the leaders and it means we have to now win them both.
"Mentally we will have better days than this."
I was delighted with Jovetic. I have always said he has great talent
Fiorentina coach Cesare Prandelli
Understandably, Fiorentina coach Cesare Prandelli was in joyous mood after the game as his side maintained their unbeaten home record so far this season.
"We were fantastic, that is the best performance I have seen by a Fiorentina side in the four years I have been in charge," he enthused.
"Liverpool did not play well but that was because of the performance of my team. We were outstanding, especially in that first half when we were just fantastic.
"The pressure we put Liverpool under all over the pitch was wonderful to watch but although we played well, I believe we can still improve - and we will have to if we are to qualify from this group.
"To have beaten such a great team with such brilliant players was an achievement but we must not waste this and we now need to keep winning in this group.
He added: "I was delighted with Jovetic. I have always said he has great talent but last season maybe he did not play for the team, now is working for everyone else and he is gaining his rewards."
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