The 24-year-old became the Reds' first addition of the summer on Thursday, after an agreement was reached for his transfer from Brighton & Hove Albion for an undisclosed fee.
It's the latest moment of joy for the midfielder in a whirlwind 12 months, having been a key figure in Argentina lifting the World Cup in Qatar at the end of 2022.
Mac Allister also helped Brighton clinch European football for the first time in their history with a sixth-placed finish in the Premier League, making 35 appearances and scoring 10 goals in the competition.
He spoke exclusively to Liverpoolfc.com at the AXA Training Centre shortly after completing a medical and signing his long-term contract – read on for the transcript...
Alexis, welcome to Liverpool FC. How does it feel?
Thank you very much. It feels amazing. It's a dream come true, it's amazing to be here and I can't wait to get started.
How pleased are you that the deal has been wrapped up so early in the summer?
Yeah, it's good for me, for the club. I wanted to be in [from] the first day of pre-season, so it's good that everything is done. I'm looking forward to meeting my teammates.
What have the past few days been like for you? I'm sure your family and friends back home must be absolutely buzzing...
Yeah! I've received a lot of messages. I was everywhere on Twitter and social media but I was very quiet and, of course, waiting for this moment.
It's been a really good past 12 months or so for you with Brighton, Argentina at the World Cup and now this move. Has it sunk in yet, or will it sink in?
As you say, it was a fantastic year for me – World Cup, what we achieved with Brighton – but now it's time to think about Liverpool and try to be a better player and a better human being every day.
Why do you feel this move to Liverpool is the natural next step in your career?
Because it's a big club. Since I arrived here, I can see how big this club is – the players we have, the staff, everyone. I'm really pleased and looking forward to playing for this club.
You've played at Anfield twice as an opposition player. The next time you'll be there, you'll be a Liverpool player – how excited are you for that moment?
Well, I have to say that I've got very good memories at Anfield – but hopefully the ones coming will be even better. I played for Boca Juniors and I feel like Liverpool is that kind of team where the fans are supporting the whole game. I'm really looking forward to playing in front of our fans and showing what we can do.
You've taken the No.10 shirt and some great Liverpool players in the past have worn that number. You've worn it at some of your previous clubs, so is there any particular meaning for you behind that number?
No, not really. I know how important the No.10 is in football. I had the possibility to take the No.8 as well, which is a big number for this club because of [Steven] Gerrard, of course. But I decided for No.10 because I used it a lot of times in Argentina, in Brighton, U23s national team as well. It's a number that I really like and that's why I chose it.
Since you've signed, have you had an opportunity to speak to Jürgen Klopp and was he a big factor in your decision to join?
I had the possibility to speak with him – he looks like a very nice guy. You can see how the players respect him and, of course, he's one of the best managers in the world. I'm really looking forward to working with him.
You've achieved big things in your career already but do you feel that this club and this team gives you a platform to keep growing and improving?
Yeah, that's the idea. Since I won the World Cup, I said that I want to win more trophies and I think that this club will help me to do that – that’s the aim and when you are in a big club like this one you have to win trophies. So, that's what I want.
Do you want to just tell us about the number of different midfield roles and positions you've played for various teams, and what skillset will you bring to this team?
Well, I've played almost in every position! And I think the managers who worked with me know that I can do it everywhere if they need me. As a player, I'm a player who tries to play as simple as possible, I try to help my teammates defensively or attacking. That's the most important thing and I'm a team player and I will try to bring that to this club.
You've been in the Premier League for three-and-a-half seasons, so are you hoping that experience will allow you to settle quickly and help the team from the start?
Yeah, 100 per cent because my first year at Brighton was very hard because of the language [and] the culture, but now I know how everything works. It will take time but once I get used to the club and everything I think everything will be good.
What do you hope to achieve as a Liverpool player over the course of your time here?
Well, win trophies, that's the aim. It doesn't matter which ones. Of course every player wants to win the Champions League and the Premier League but I will do my best to help the team and try to win every trophy.
Finally, what's your message to the Liverpool supporters who are reading this interview?
That I'm sure this team will give everything to win trophies and make them happy, that's the most important thing. I hope they stay behind me and behind the team and I know they will do it, so it's a pleasure to be here at this club and I will do my best every single day.