The boss confirmed on Monday that Naby Keita, who missed the 2-0 win over Watford at the weekend, is available for Tuesday’s match at Estadio da Luz, along with Trent Alexander-Arnold, Curtis Jones and Joel Matip.
Alexander-Arnold was an unused substitute for the Reds’ 10th consecutive Premier League victory on Saturday following a hamstring injury, while Jones and Matip each picked up knocks against the Hornets.
Klopp said: “Yes, full squad available, absolutely.
“Curtis was just a little swelling, [it] disappeared then overnight, fine. Same with Joel, which is really helpful because it looked really strange. Yes, and Trent trained now four or five days, I’m not sure exactly, but yes, he is ready as well.”
Diogo Jota and Sadio Mane would be suspended for the second leg should they get booked in Portugal.
For Benfica, Rodrigo Pinho and Lucas Verissimo are long-term absentees, but striker Haris Seferovic returned from injury as a substitute in Friday's 3-2 defeat to Braga.
Meanwhile, seven of the hosts' players are a yellow card away from missing the return game at Anfield, including Nicolas Otamendi, Julian Weigl and Rafa Silva.
Last match
Braga 3-2 Benfica (April 1): Vlachodimos, Gilberto, Otamendi, Vertonghen, Grimaldo, Weigl, Meite, Ramos, Everton, Silva, Yaremchuk.
Liverpool 2-0 Watford (April 2): Alisson, Gomez, Matip, Van Dijk, Robertson, Henderson, Thiago, Jones, Firmino, Jota, Salah.