Sergio Busquets pinpointed last month's 1-0 victory over Atletico Madrid as the moment Barcelona knew they could regain the La Liga title this season.
Barca were crowned champions for the seventh time in the past 10 campaigns as Lionel Messi scored a hat-trick to inspire a thrilling 4-2 win at Deportivo La Coruna on Sunday.
It is a triumph that has, for the most part, had a certain inevitability about it, but Atleti could have closed the gap to within two points had they won last month's meeting at Camp Nou.
Messi was again the hero on that occasion, though, and Busquets believes the 1-0 win was crucial to Barca's 25th La Liga title.
"The win at home against Atleti when it was such a big deal to win at home, that was a key moment, it showed we never gave up," Busquets told reporters pitchside after the game.
"It [winning his seventh La Liga title] has just kind of been like all of them, every year it passes it costs more to do.
"It's terribly difficult to think of all the tests we have to go through, to do it with four games going is a great achievement. It's been an almost perfect campaign, we haven't lost yet."
Current mood! April 29, 2018
Busquets also paid tribute to Andres Iniesta, who announced this week that his 22-year association with Barcelona will come to an end at the conclusion of the campaign.
Iniesta was consigned to a late cameo after Barca had seen a two-goal lead wiped out before Messi struck twice in the closing stages.
"When you say goodbye to a great player, a great man, it's partly a sad thing, but he's earned the right to say what he'll do," he added.
"Leaving this way is the right manner to do it. For us he's everything, the brand of this era, and he won the World Cup with the national team.
"I've played 10 years winning trophies with him, playing with him is like playing with a legend.
"I'll enjoy every minute with him, and then hopefully with Spain in the World Cup. It's goodbye in football terms, but the praise said of him is not enough to properly do him justice."
