Yossi Benayoun hit a treble as the Reds roared to the biggest Champions League win by any side.
But boss Benitez said: "Porto need to come here and they will be worried and wary for sure now.
"They are experienced and may not feel the pressure, so we have to put pressure on them on the pitch.
"We know we have been creating chances recently but not scoring too many, so tonight it was good to see them going in.
"Does it increase my belief we will go through? Well, we had the belief anyway and know we need to win the last two.
"If we do we'll be there. At least we will have confidence against Porto after that performance.
"You always try to win trophies and get in the record books. If you can't win a trophy but get in the record books, at least it's something."