Alisson insists that added focus was the key to Liverpool finally recording back-to-back clean sheets after they booked their place in the Champions League knockout stages.
Jurgen Klopp's men finished top of Group E by beating Red Bull Salzburg 2-0 in Austria on Tuesday.
A Naby Keita header gave Liverpool the lead in the 57th minute at Red Bull Arena, before Mohamed Salah doubled their account with a wonderful finish from a tight angle moments later.
The reigning European champions will now have the chance to defend their crown in the new year, with Napoli also progressing after beating Genk 4-0 on the same night.
Liverpool hadn't registered a clean sheet in any competition since late September prior to their 3-0 victory away at Bournemouth in the Premier League on Saturday.
However, after managing another shut-out three days later in Europe, Alisson detailed the reasons behind their improved defensive performances.
“It was just a matter of time and of focus,” the Reds goalkeeper told the club's official website.
“The last two games, we were focused for the full game. Even if they had chances we were there, the defenders were there and I was there to help the team.
“We just need to keep going with this focus because we know our quality and we know what we can do on the pitch when we put in our whole intensity.
“You need to do that for 90 minutes – it’s hard, we know, but I think we showed we can do this.”
Alisson was forced to make a number of important saves in the first-half against Salzburg, who looked threatening in the final third with Erling Haaland, Takumi Minamino and Hwang Hee-chan leading the line.
The Brazilian went on to reveal what was said in the dressing room at half-time to spark Liverpool's bright start to the second period.
“The message was just to keep going and keep working,” Alisson added.
“In the first half they made our job more difficult with the intensity they put in; they had chances, of course, but we neutralised them in the chances, I could make the saves.
“I’m happy with the result and happy with what we did on the pitch.
“It was a difficult game for us but we did very well, everybody playing together and moving together, defending in a good way and attacking in a good way.
“I’m glad about the score, I’m glad about the clean sheet – but the three points were the most important thing we needed.”
Liverpool will now look ahead to a Premier League clash with Watford at Anfield on Saturday, where they will look to extend their advantage at the top of the table.