Last March, Romelu Lukaku went to Ole Gunnar Solskjaer's office and told the Manchester United boss that he felt it would be best for both parties if he left at the end of the season.
"I wasn't performing and I wasn't playing," the striker later explained.
With Marcus Rashford and Anthony Martial ahead of him in the pecking order, and Mason Greenwood just breaking into the first team, Lukaku felt that his exit would be a "win-win situation" for everyone involved.
Just under a year later, Lukaku has undeniably benefited from his departure. The same cannot be said of United, though.
Greenwood may have since confirmed his potential as one of the most promising players to have emerged out of United's academy in years but Rashford is presently out injured and Martial is struggling terribly in his absence.
Lukaku, by complete contrast, has been reborn at Inter, for whom he has netted 20 times in 29 outings since joining for £75 million ($98m) last summer. United are now counting the cost of failing to replace the 26-year-old.
As former Red Devils midfielder Paul Ince recently told Paddy Power, "If Ole wasn't already regretting letting Lukaku go, he seriously will be now.
"I'll be the first to admit that I had a go at him at times, and he can't retain the ball, but you do get 20-25 goals a season from him."
Lukaku hit 27 in his first season at Old Trafford, in 2017-18, but, as he acknowledged himself, his form tailed off dramatically last term.
The former Chelsea attacker may have played a pivotal role in Solskjaer's successful spell as caretaker coach, netting twice in the dramatic Champions League win over Paris Saint-Germain at the Parc des Princes, but it is worth noting that he didn't score a single goal after the Norwegian was confirmed as United's permanent boss at the end of March.
Just six starts followed that famous night in the French capital. Essentially, once Solskjaer got his feet under the table, he started looking to the future – and Lukaku didn't feature in it.
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Lukaku has since claimed that the current manager's predecessor, Jose Mourinho, didn't have the players he needed to succeed in Manchester. But it's clear that he views his own spell in the same light.
Solskjaer favoured a more mobile attack, featuring Rashford, Martial and Jesse Lingard, and while Lukaku is tactically versatile - he can be hugely effective out wide, as he showed against Brazil in the 2018 World Cup - movement is not his greatest strength, which is perhaps unsurprising for a player of his size.
Of course, that could have been forgiven at Old Trafford if Lukaku had proven himself a formidable target man but his inconsistency when it came to holding the ball up became a huge source of frustration.
Zlatan Ibrahimovic, who will be on the opposite side for Sunday's Milan derby, told the Gazzetta dello Sport last year that he was astounded by Lukaku's poor control during their time together at United and made a bet with his fellow forward that he would give him "£50 for every decent first touch".
To the Swede's immense frustration, Lukaku never accepted the wager: "Perhaps he was afraid of losing?!"
However, even Ibrahimovic predicted that his former team-mate would do well at Inter because of his "sheer power", a power that Antonio Conte was perfectly placed to harness.
Conte had long coveted Lukaku. He tried to sign him twice before - first during his time in charge of Juventus and then after he had taken over at Chelsea.
Crucially, Lukaku rated Conte just as highly. After a friendly between Belgium and Italy in Brussels in November 2015, the attacker had been struck by the Azzurri's style of play.
The hosts had won the game 3-1 but Lukaku was impressed by just how many chances been created by and for Conte's front two, Graziano Pelle and Eder.
“I understood that with his style of playing," he told Tiki Taka, "I would have had a lot of chances to score and it would enhance my physical abilities."
“After the game, we talked a little and he told me that he was going to Chelsea, but it wasn't possible for me to follow him there. So, I told him that if he went somewhere else in the future, I would follow him.”
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This mutual appreciation fuelled Lukaku's move to Inter, despite interest from Juventus.
Questions were raised in Milan about the club-record fee but Conte was acutely aware of both Lukaku's strengths and weaknesses and, crucially, he was willing to do something that Mourinho couldn't do, and Solskjaer wouldn't do: build an attack around Lukaku.
Indeed, as the striker has admitted himself, he excels when surrounded by players adept at creating and exploiting space with intelligent running and crisp passing.
"When there is a lot of movement around me, here (at Inter) and with the Belgian national team, I am at my best because then I can contribute myself and I can be at the end of the delivery,” he told Sky Sports.
"Right now, the systems we are playing, here at Inter with the 3-5-2, and with the Belgium national team in a 3-4-3 with players close to me."
Conte does not quite have the same amount of creative talent at his disposal as Roberto Martinez, but the January signing of Christian Eriksen should go a long way towards rectifying that dearth of innovation in midfield.
And besides, at Inter, Belgium's all-time record goalscorer gets to play alongside Lautaro Martinez, the perfect foil for Lukaku with his pace, positioning and precision.
This is a perfectly complementary, old-school 'small-man big-man' pairing that has sustained Inter's Scudetto challenge and the shame is the Argentine is suspended for this weekend's Milan derby.
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However, with his similar level of industry, the fit-again Alexis Sanchez could prove an able deputy. Lukaku will go into the game on a high having netted both goals in last weekend's win over Udinese, which ended Inter's run of three consecutive Serie A draws.
The double also means that Lukaku has scored as many league goals this season as he did for United over the course of the entire 2017-18 campaign.
Lukaku may still have his flaws and he continues to be nagged by allegations of being a flat-track bully but he has undoubtedly improved since leaving Old Trafford.
He says he learned a lot at United. And from Ibrahimovic.
"I remember one training session," he told United's official website. "Because we were both strikers, we were never on the same team and, at one point, there was a 50/50 challenge. He went full-on against me! That is when I knew this guy wants to compete and this guy wants to fight for his spot.
"That is why he changed me. It was an eye-opener. The guy had to fight to be in the position he is in. So, I learned just to focus, work hard and enjoy it as well."
So, while Lukaku may not have taken that bet, he did take plenty away from playing alongside a man he describes as "a great champion and professional".
He has no regrets over telling Solskjaer last March he wanted to leave United. One wonders, though, if Solskjaer regrets letting him go.