Jurgen Klopp's charges head to Portugal with a 2-0 advantage from the first leg after goals from Naby Keita and Roberto Firmino, and the omens don't look good for the Primeira Liga side.
Porto suffered their heaviest ever home defeat in European competition against Liverpool in last season's Champions League, with the Reds winning 5-0 in their last-16 tie.
Indeed, Liverpool have never lost a European match against Porto in seven previous encounters, keeping three successive clean sheets against them (Opta Stats).
Since the start of last season, the Reds have won three of their four away Champions League knockout games, although in Porto's favour, they are the only remaining side in the competition to have won 100 percent of their CL home games this season.
Speaking ahead of the game, Nicholas suggested that Klopp will probably not make many changes to the team, although the midfield could be rejigged, and stated it could prove an "awkward" game, albeit getting the job done in the end.
"In reality, Liverpool could make changes to the team in this one, but they do not want to take advantage, especially if they go a goal down," Nicholas told the Sky Sports News website.
"Mohamed Salah is back in form and Sadio Mane scored again at the weekend, while Roberto Firmino has been the best of the attacking players recently. He may not take any chances but he may change the midfield. It will be awkward but Liverpool will get the job done and be comfortable towards the end in this one."