The Reds' number one was welcomed back to the starting lineup for their showdown with the La Liga upstarts at Estadio Montilivi, two months on from suffering a hamstring injury against Crystal Palace.
Number two Caoimhin Kelleher held the fort in exemplary fashion while his superior was sidelined, but Slot did not hesitate to throw Alisson back into the starting XI, affirming that the Brazilian remains his undisputed number one.
Slot's call was completely justified on Spanish soil, as Alisson kept a spirited Girona at bay with five crucial saves, including a couple of one-on-one stops and a brilliant leap to deny Yaser Asprilla from long range.
Speaking to the media in his post-game press conference, Slot light-heartedly suggested that his outfield players wanted to make sure Alisson was 100% fit by giving him so much to do, while also expressing his belief that the South American is the best in the world in his position.
Slot: 'Alisson showed why he is number one'
When a journalist suggested that Alisson looked like he had never left, Slot replied: "No, he definitely didn't. I said a bit of a joke that maybe the players wanted to see how fit he really was, so to give him so much work. But, of course, that was not our plan.
"He showed again today why I said so many times that he's our first goalkeeper. That has nothing to do with Caoimhin [Kelleher] - he did so, so well. But Alisson has been so important for this club for so many years, for his country as well.
"[He] showed today that he's probably one of the best, in my opinion the best goalkeeper in the world. And let's hope he can keep continuing to bring these performances. Let's hope even more that he can stay fit."
After Alisson was forced into a few first-half interventions, Liverpool drew first blood just past the hour mark through Mohamed Salah, who struck his 50th European goal for the Reds and 50th Champions League goal from the penalty spot after Luis Diaz was fouled by Donny van de Beek.
Liverpool were keeping Paulo Gazzaniga busy throughout the battle, but their triumph was far from straightforward, as Girona wide men Bryan Gil and Arnaut Danjuma sought to cause havoc at every opportunity.
Slot admits there was "a lot" he disliked about Liverpool performance
Nevertheless, Liverpool's slender success keeps them at the top of the 36-team UCL table with a perfect record of 18 points from 18, although Slot was not at all satisfied with his players' performance.
Asked if there was anything he disliked on Tuesday, the Dutchman replied: "A lot, but especially two things. If you play against a team that has such a good idea about football, knows how to bring the ball out from the back - like some other teams we faced recently, like [Manchester] City or Real Madrid - then you need to be so intense if you want to make it difficult for them.
"But if every time you are waiting a few seconds before you press, and if you do press you are so easily outplayed, then this team can cause you a lot of problems. I almost feel sorry for them because they deserved so much more in this Champions League campaign than the three points they have until now. But we have an incredible goalkeeper.
"The other part was every time we lost the ball we were not aggressive enough, so every time we lost the ball they could almost every time go all the way to our goal, having a shot or a blocked shot, and then we could attack again. Hardly any control at all over the game; maybe the second half was a bit better, but then I am trying to be positive."
Liverpool now gear up for their return to Premier League action at home to Fulham on Saturday, after last weekend's Merseyside derby with Everton was postponed due to Storm Darragh.
Written by
Ben Knapton