Alisson Becker and Virgil van Dijk have been the backbone of Liverpool's success in recent years, but Andoni Iraola and Liverpool's hierarchy cannot afford to get complacent

It may be an oft-used quote, but that doesn't make it any less appropriate for the concern looming on the horizon for Andoni Iraola and Liverpool.

And while one of the Basque's predecessors, Jurgen Klopp, was the self-confessed Rocky Balboa advocate, the Reds head coach will surely be in agreement with the gut-punching universal message.

"Time takes everybody out," says Sylvester Stallone's fabled character when explaining, years later, how he managed to beat the seemingly invincible Apollo Creed. "It's undefeated."

Nothing lasts forever. And when best to bring an end to a glittering Anfield career is the issue with which Liverpool and two of their greatest-ever players are now beginning to grapple.

The matter was brought into sharp focus on Wednesday night when both Alisson Becker and Virgil van Dijk were among those struggling to consistently maintain their level during an ultimately dire 3-2 Champions League defeat at Fenerbahce.

For Van Dijk, there was some mitigation, having been caught heavily several times during the opening moments by overly-aggressive challenges from the home team and seemingly hampered physically as a consequence. That said, given how Chelsea youngster Emmanuel Emegha shoved over his Dutch compatriot the previous week, such buffeting is in danger of becoming a regular occurrence for Van Dijk. At 35, he is understandably not quite at his physical peak and opponents will be looking to capitalise on any sign of weakness.

And the Netherlands international has reached the point in his career where he must concentrate on looking after himself and his own game, rather than having to cajole his centre-back partner and left-back through the game.

Jeremy Jacquet has been of huge benefit of that regard in the heart of defence this season. But with Jacquet having a tough time coping with Romelu Lukaku in Istanbul, it forced Van Dijk into more defending than he has been accustomed of late. And while there was an uncharacteristic error to gift Villarreal a goal last month, the importance of the skipper remains undiminished, with no player having featured for more minutes under Iraola.

Next in that list is Alisson, who turned 34 last month. It has been a tough week for the Brazilian, at fault for initiating Arsenal's winner on Sunday and then uncertain at key points during midweek. It could be argued the weekend aberration owed as much to tactical demands with Liverpool encouraged to play the ball out from the back.

And while there was nothing he could do about the deflected opener at Fenerbahce, there was a breakdown in communication with Cody Gakpo that left him stranded for the second, and then a curious reluctance to leave his goalline to clear out a high ball for the winner.

In isolation, such errors are par for the course for any goalkeeper. It happens. But it continues a gradually downward trend for Alisson who, not unlike Van Dijk, remains integral for Liverpool - particularly regards much-needed leadership and experience - but has gone beyond his peak.

Indeed, there were several reminders in the Fenerbahce team of players who have served their Premier League purpose in Lukaku, Nathan Ake, N'Golo Kante and Alisson's fellow Brazil goalkeeper Ederson, who is a year younger at 33.

Managing the inevitable decline of long-serving legends is not easy. Brendan Rodgers had to ease out Jamie Carragher and Steven Gerrard from the starting line-up - the exclusion of the latter from a Champions League game at Real Madrid effectively sparking the beginning of a painfully long end for the Northern Irishman as boss - while the difficulty Arne Slot had in coping with a fading Mohamed Salah last season remains fresh in the memory and contributed to the Dutchman also being sacked.

Iraola will hope for a more positive outcome similar to that of Klopp, who successfully negotiated the exits of stalwarts such as Sadio Mane and Roberto Firmino along with the more surprise departures of Jordan Henderson and Fabinho.

Part of the reason was the recruitment to replace those players. While not always perfect - Darwin Nunez was never the long-term answer up front - it ensured Liverpool remained competitive, winning the League Cup in 2024 and the Premier League title the following year.

The Reds will feel they have already taken such steps to future-proof the centre-back and goalkeeper positions. Giovanni Leoni, close to a return to training after more than a year out, was brought in for an initial £26million from Parma last season while Jacquet cost a potential £60m this year.

Giorgi Mamardashvili arrived last summer in a £29m deal from Valencia as a long-term successor to Alisson, but Liverpool have already perhaps shown their hand that plan may have changed with a £30m agreement for highly-rated Belgian teenager Lucca Brughmans of Genk.

Of course, £75m Van Dijk and £65m Alisson are prime examples of Liverpool getting their big-money spending right in the market, something that hasn't always been the case in subsequent years. The duo are both out of contract at the end of this campaign - indeed, there was a possibility Alisson could have gone in the summer with Juventus keen - and the drop-off from Salah last term was a reminder judging when best to part ways is not an exact science.

But if it would be a surprise should both Van Dijk and Alisson further extend their Anfield careers, it wouldn't be a shock if neither was at the club next season.

For now, though, they remain the undisputed first-choice options for Liverpool in their respective positions. Even no longer at their best, they are still crucial to helping Iraola usher in a new era - even if the duo may not necessarily be part of it. The baton is being handed over.