This time was inevitably going to come. When Barcelona signed Claudio Bravo and Marc-Andre ter Stegen as replacements for Victor Valdes in the summer of 2014, the Chilean was the experienced head in La Liga, the German a man for the future. So letting the South American leave merely means that things are going to plan.
Bravo has been everything that the Catalan club had hoped he would be. Having spent several years at Real Sociedad, he came in and provided experience in La Liga in Luis Enrique's debut season while Ter Stegen started in the Champions League and the Copa del Rey. In the end, Barca won it all that year - and the two goalkeepers were excellent.
In his second season at Camp Nou, the Chilean came in to steady the side after a difficult month for Ter Stegen at the beginning of the campaign. Barca's defence had been shaky and again his experience proved vital. As in his debut campaign, Bravo was first choice in La Liga, with Ter Stegen preferred in the cup competitions. Again it worked well - and the Catalans claimed the Primera Division once more.
But both men wanted more. No elite goalkeeper is content with a bit-part role - even at a big club like Barca - and after winning the Copa America for a second successive summer, Bravo came back with a demand: he wanted to be the undisputed starter. And after sitting on the bench for Germany at Euro 2016, Ter Stegen returned with a similar request. So something had to give.
At his first press conference in pre-season, Luis Enrique said that he was delighted with his two goalkeepers and that he wanted them both to stay along with third-choice shot-stopper Jordi Masip. And that, of course, was true: any coach seeks to have the best-possible options at his disposal.
In the meantime, speculation grew that the club could dispense with one of Bravo or Ter Stegen but Barca kept quiet. Had they admitted that they were willing to sell, the price of either man would have dropped immediately - and there was no need to talk about it.
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Ter Stegen is currently injured and will be out for two-to-three weeks. That means that the timing of the imminently expected sale of Bravo to Manchester City is far from ideal. The Chilean will end up moving to the Premier League when he is needed at Camp Nou but keeping him at the club would only create a problem when the German is back and Barca can cope without him.
Luis Enrique trusts Masip to start if necessary and will move to sign a replacement for the Chilean, in any case, with Valencia's Diego Alves topping the list. The Brazilian has experience in La Liga, is a penalty specialist and would not expect to start every match. He would be ideal backup for Ter Stegen.
Bravo has been a superb servant but the time to sell is now. The fee, €25 million, represents brilliant business for a goalkeeper brought in for less than half that (€12m) and one who has impressively overseen a transition between the sticks at Camp Nou after the traumatic departure of club legend and long-time incumbent Valdes.
In the meantime, Ter Stegen will go on to become one of the best goalkeepers in the world, perhaps even the finest of them all. At 24 years old, the German is the future for Barca and at Camp Nou, Bravo is now the past. So although Luis Enrique would have liked to have held on to the Chilean for one more season, this moment was part of the plan from the very beginning - and the changeover from Valdes to Bravo to Ter Stegen is now complete.