Hard to predict. Depends on how focused and sharp Liverpool come out, they tend to play much better at home. The atmosphere does play a role and if Anfield is up for it like it was against Chelsea or Juve in the CL last season it could have a big impact but like Vinnie said if Benfica can withstand the pressure the first 25-30 mins and they are solid at the back then things can even out more but the pressure is on Liverpool because the only way they 'might' be safe is by scoring three goals or else they'll have to be very solid on defense and a bit lucky not to concede (which they are capable of).