Benitez warned that Ken McKenna's side would be fitter than the European champions ahead of tonight's first round qualifying tie first leg at Anfield.
"TNS have played more friendlies and have been training longer, so they will be better than us physically," he said.
"But we have quality and we must use that quality. If we try to play like them it will turn the game into a final, and we know we must be careful."
Benitez has also told his side to put all memories of their momentus final win just 7 weeks ago to the back of their minds.
We cannot think about the past. You have to work for the future and we must prepare properly for every game - like this one - because if we are caught sleeping and dreaming about the past we will be punished."
"Benitez also voiced fears over the lack of time his side has had to gel together.
"We have signed some new players and the international players only arrived a week ago so it won't be easy," he said.
"Only half of the squad have been training for two weeks and the rest for one week, so I don't know which team we will see."
Despite these concerns by Liverpool's boss, they remain overwhelming favourites to progress to the next round, such is the difference in class between Liverpool and the Welsh Premier League.