Now it will be a case of finishing the job to ensure progression to the semis and a two-legged tie with FC Barcelona, with Klopp opting to make alterations in midfield to achieve that objective.
Robertson missed the first leg through suspension, while Milner and Wijnaldum were both subs against Chelsea on Sunday.
Meanwhile, the Reds have a strong-looking bench with plenty of attacking options, should Klopp need to turn to them late on.
Joe Gomez is the main defensive option after returning to fitness recently.
Porto return to their usual 4-4-1-1 system for European matches, with Otavio playing off central striker Moussa Marega. Hector Herrera is back in midfield after suspension, as is Pepe in defence—meaning Militao moves to right-back.
Substitutes: Mignolet; Gomez, Henderson, Keita, Shaqiri, Sturridge, Firmino.
Porto: Casillas; Militao, Pepe, Felipe, Telles; Corona, Danilo, Herrera, Brahimi; Otavio; Marega.
Substitutes: Vana, Maxi, Bruno Costa, Oliver, Andre Pereira, Tiquinho Soares, Fernando Andrade