Beaten at Tottenham on the opening weekend, they recovered to over-power Stoke in midweek, only to slump to a disheartening 3-1 home defeat at the hands of a vibrant Aston Villa at Anfield.
It was Villa's first win of the season, and ended Liverpool's 31-match unbeaten league run dating back to December 2007.
And the reverse already puts in doubt Liverpool's title aspirations. They only lost two league games last season, now they have equalled that tally in the opening days of the new campaign.
Villa were two-up at the break through a Lucas own goal and a header from Curtis Davies. Torres pulled one back in the second-half, but Steven Gerrard's lunge at Nigel Reo-Coker conceded a spot-kick that Ashley Young confidently drove home.
Benitez said: "In the first 20 minutes we created plenty of chances and played well. Then we conceded the own goal and started to make more mistakes.
"We have lost and we know we have to improve. I felt we had a chance when Fernando Torres scored, but the penalty finished it. It was a clear penalty.
"We now know that we have to go to Bolton on Saturday and win. Everything could change if we do that, our confidence will improve."
Benitez added: "We were not playing well, and we were up against a team who are excellent on the counter-attack.
"Their keeper (Brad Friedel) made some great saves, but when that happens we just have to make more chances.
"This squad is virtually the same as last season, so I believe it is good enough to mount a title challenge. But we must do more, we must win at Bolton.
"We will have to sit down and analyse every player now, and make sure we do the right things in our next match. But our senior players must take more responsibility."
Villa boss Martin O'Neill said: "That was a terrific effort from my team. At 2-0 we were in reasonable command of the game, although you are never in command at Anfield.
"But when they scored we got a penalty straightaway, a clean penalty, and we were back with our two goal lead.
"That gave us confidence, discipline and shape to our team and we deserved to win.
"Brad Friedel was outstanding. He rolled back the years. He was fantastic against his old club to perform like that at Anfield.
"He will be delighted with himself, and rightly so, and we are delighted with him."
"It was a fantastic performance from the whole side and we fully deserved the victory."
