Christian Horner says Red Bull did all they could to keep hold of Daniel Ricciardo and compared his departure to the break up of a relationship.
Ricciardo will drive for Renault in 2019 after five seasons with Red Bull, who embark on a new era powered by Honda.
Pierre Gasly has been promoted from Toro Rosso to partner Max Verstappen for the forthcoming season, but team boss Horner said the original preference was to hang on to Ricciardo.
"We looked at it and I think we did everything that we possibly could to retain him," Horner told Autosport.
"He actually said this - he did the classic break-up - it's not you, it's me! And I think he just genuinely wanted to take on a new challenge.
"I think he was also probably concerned about his value with the evolution of Max and was probably uncertain about Honda at that time.
"Subsequently he's seen what we were talking about start to come to fruition.
"You always have a plan B. I think once we understood that he was serious, that that was his mindset, it was a very easy decision to come to regarding Pierre Gasly."
Horner also rejected that Verstappen had become Red Bull's number one driver.
"The number one driver in this team is the driver who is ahead on the track. That's the simple rule," he insisted.
"And there is zero favouritism in the way that we operate the team, from one driver to the other. Daniel will tell you that very openly.
"Mexico was the first time that Daniel outqualified Max since Monaco. Max's qualifying performances have been huge, and that was probably part of Daniel's decision taking for the future."
|It can happen – Allegri plays down Ronaldo penalty miss|
|Mavericks´ Doncic becomes second-youngest player to record triple-double|
|Yankees send Sonny Gray to Reds|
|Ashley Cole reunited with Frank Lampard at Derby County|
|Arnold ready to mix things up in 2019 Asian Cup quarter-finals|
|Arum: Joshua desperately needs to fight in the United States|
|South Korea v Bahrain: Bento optimistic of continuing unblemished campaign|
|Bolton Wanderers 0 West Brom 2: Baggies bounce up to third after tennis ball protest|
|Confident Moeen ready to shine for England in the Caribbean|
|Juventus 3 Chievo 0: Allegri´s men cruise despite Ronaldo penalty save|
|Boateng completes shock Barcelona switch|
|United Arab Emirates 3 Kyrgyzstan 2 (after extra time): Khalil penalty sets up Socceroos showdown|
|West Indies add Drakes to new-look coaching team|
|Barcelona is a huge opportunity – Boateng confirms shock move is close|
|Donnarumma wishes Higuain luck ahead of expected Chelsea switch|
|Qatar v Iraq: Katanec anticipating ´huge challenge´ in last 16|
|Nuno hit with FA misconduct charge for pitch celebration|
|Furious Carreno Busta and Zverev bow out, Djokovic marches on|
|#NotMartinFromWakefield – Siewert shows viral sensation the door|
|Djokovic feeling the strain after late-night Medvedev battle|
|Henderson sidelined again ahead of Six Nations|
|Australia 0 Uzbekistan 0 (aet, 4-2 on penalties): Ryan heroics see holders hobble onwards|
|Halep exit leaves four-way fight to be crowned number one at Australian Open|
|Super Bowl-bound Rams set for London return, Chiefs to face Chargers in Mexico|
|Huddersfield appoint Siewert as Wagner´s replacement|
|Genoa 0 AC Milan 2: Borini and Suso step up with Higuain left out|
|McTominay signs new Manchester United contract|
|Pizzi to stand down after Saudi Arabia elimination|
|Boateng closing in on shock Barcelona switch - reports|
|Catalans to defend Challenge Cup after resolving RFL dispute|
|Djokovic wears down Medvedev to reach last eight|
|Mouratoglou: I knew ´loyal´ Serena would not fire me after US Open turmoil|
|Barcelona B defender Wague accuses Ejea fans of racist abuse|
|I felt like I had been hit by a train - Halep upbeat despite losing Serena battle|
|Arsenal confirm Mislintat departure|
|Icardi will renew, 100 per cent - Wanda Nara offers latest Inter assurance|
|Japan 1 Saudi Arabia 0: Four-time winners send Pizzi´s men out|
|A souvlaki maybe named after him, a growing fan base – Tsitsipas creating Melbourne buzz|
|Barca winger Dembele out for 15 days|
|Strikers blown away by Hurricanes in Adelaide|
|Ireland lose Beirne for England and Scotland clashes|
|´Innate fighter´ Serena says character key to beating Halep|
|Hudson-Odoi ´an outstanding talent´ - Bayern great Ballack hails Chelsea youngster|
|Scotland call up four as hand injury forces Watson out|
|Serena comes through major Halep battle to reach last eight|
|Better than Rafa? Camacho cameo leaves Klopp unconvinced by transfer options|
|England job ´a privileged position´, says Southgate|
|Emery has confidence in Arsenal outcast Ozil|
|Zverev destroys racquet in Aus Open meltdown|
|From Villarreal to Aus Open quarters – Bautista Agut breaks major duck|
|Brees: I plan on being here next year and making another run at it|
|´Unf******-believable bro!´ - Brady stunned after reaching third straight Super Bowl|
|New England find answers, penalty costs Kansas City – three takeaways from Patriots´ win over Chiefs|
|Donald Trump congratulates Brady and Super Bowl-bound Patriots|
|Rose helps Timberwolves down Suns|
|Brady leads Patriots into third straight Super Bowl|
|Osaka overcomes Sevastova to reach quarters|
|Chelsea remain behind Sarri – David Luiz|
|McVay explains Gurley´s limited role in Rams´ win over Saints|
|Southgate hails ´tremendous talent´ Rashford|
|Long earns maiden PGA Tour win at Desert Classic|
|Flanagan resigns as Sharks head coach|
|Rams´ Robey-Coleman admits he committed penalty on controversial no-call|
|NFL admits they blew the call – Saints coach Payton|
|Terrible no-call, Goff shines – three takeaways from Rams´ win over Saints|
|Lonzo Ball to miss 4-6 weeks with ankle sprain|
|Patterson added to Australia Test squad|
|Zuerlein´s overtime kick sinks Saints and sends Rams to Super Bowl|
|It was a clear goal – Valverde dismisses Barca VAR controversy|
|Rashford can emulate Man United greats Ronaldo and Rooney – Solskjaer|