The Reds hold a commanding 5-0 lead from the first meeting last month, when Sadio Mane’s hat-trick and goals from Mohamed Salah and Roberto Firmino stunned the Portuguese league leaders.
But Sergio Conceicao’s side have won all four of their matches since that night and Klopp’s respect for Porto will strongly influence the line-up he selects at Anfield on Tuesday.
“It’s not about rest. We have to see,” said the manager immediately after the Premier League win against Newcastle United at the weekend.
“I have not thought a second about the line-up against Porto, but they have won all their games since we played them. They now have a big lead ahead of Sporting. They will strike back, that’s what they want.
“They are Portuguese and proud and will give a fight. They want to strike back. If anybody here thinks they come here and give the game up, leave their star players at home or whatever, they are mistaken.
“It’s Champions League and the whole world is watching. I don’t think for a second about resting anybody.
“I know it’s Manchester United afterwards but we cannot change it. We can’t say, ‘now we pick this and rest him’.”