They like a defining moment at Anfield, especially when it comes to the Champions League, and they now have one to cling to all the way to Madrid next June, thanks to Alisson.

You get what you pay for, and Alisson -- who cost a then-world-record-for-a-goalkeeper £67 million when he arrived from AS Roma during the summer -- earned his place in Liverpool folklore with the stoppage-time save from Arkadiusz Milik that proved the difference between success and failure in Group C. Had Milik's effort ended up in the back of the net, Liverpool would have been facing a Europa League campaign in the second half of the season.

But thanks to Alisson getting in the way of the shot -- Milik directed his effort too close to the Brazil No. 1, but he still had to be in the right place at the right time -- Liverpool can look forward to next Monday's draw for the Champions League round of 16 with hopes still alive of a place in next June's final at Atletico Madrid's Wanda Metropolitano Stadium.

"I have no idea how Alisson made a save like this," Liverpool manager Jurgen Klopp said after the game. "It was amazing."

Champions League glory can often be decided by such fine margins, as Liverpool know better than most.

Alisson's save on Arkadiusz Milik saved Liverpool's Champions League campaign and could define their season. Getty Images

This 1-0 victory over Napoli came 14 years to the day after Steven Gerrard's late goal against Olympiakos at Anfield confirmed a crucial 3-1 winning margin that took Rafael Benitez's team into the knockout stages on goal difference ahead of the Greek champions. Six months later, Liverpool were lifting the European Cup for a fifth time in Istanbul after their remarkable fight back against AC Milan, and it could all be traced back to Gerrard's goal against Olympiakos.

Will Alisson's save prove to be as pivotal as Gerrard's goal? Time will tell, but there was another pivotal moment in last season's campaign, and that also involved a goalkeeper. On that occasion, Loris Karius' failure to hold onto Gareth Bale's long-range strike in the final against Real Madrid in Kiev put the Spanish team 3-1 ahead and out of reach.

Big moments decide big games, and Liverpool discovered in Kiev the cost of not having a world-class goalkeeper.

Against Napoli, they enjoyed the flip side. They spent big to get their man in the summer, and he repaid a huge chunk of his fee with the save from Milik that took Liverpool into the business end of the Champions League.

Mohamed Salah's first-half goal had given Liverpool a 1-0 lead that they knew would be enough to secure qualification, and it was a sensational goal by the Egyptian. Salah forced Napoli defender Kalidou Koulibaly into his one mistake of the night by ghosting past the Senegalese international before beating David Ospina with a low, right-footed strike.

On its own, that moment of magic would deserve to claim any headlines, but Alisson's save was the decisive contribution. Milik was unmarked inside the 6-yard box when he received the ball. He shot goalward, but Alisson spread himself to smother the shot and was able to block it with his outstretched right leg.

Save made, job done, game won. And £67 million well-spent.

A year ago, Liverpool were preparing to sell their best player by sanctioning Philippe Coutinho's £142 million transfer to Barcelona. At the time, it looked as though Liverpool were selling the family silver and surrendering once again when a giant club came along to take their top talent, with Coutinho following the likes of Michael Owen, Xabi Alonso, Fernando Torres, Luis Suarez and Raheem Sterling out of the door at Anfield.

But instead, Klopp was allowed to reinvest the Coutinho money by signing Virgil van Dijk for £75 million in January and Alisson in the summer. With the money they banked from Coutinho's sale, Liverpool recruited Van Dijk and Alisson, and they have become a stronger team as a consequence. The two players have given Liverpool a solidity at the back that is borne out by the fact that this 1-0 win was their 15th clean sheet in their past 19 home games.

Van Dijk, who was fortunate to escape a 13th-minute red card for a bad tackle on Dries Mertens, is a totemic figure who has organised the once-leaky back four. The yellow card he received for the Mertens foul will see him suspended for the first leg of the round of 16, and Liverpool will miss him.

With Alisson behind the back four, Liverpool have a last line of defence up there with the best in the world. His save from Milik evoked memories of Peter Schmeichel at his best at Manchester United or Gianluigi Buffon in his pomp for Juventus. It was that good and that important.

Was it a defining moment? It could well be. With Alisson in goal, Liverpool know they can beat anybody.