When will Manchester City regret allowing Cole Palmer to join Chelsea: now, in the future or never?

It is 192 days since City appeared to have unearthed a gem from their academy, as Palmer came off the bench to curl in an equaliser against Arsenal in August's Community Shield at Wembley. City went on to lose both that game (on penalties) and Palmer himself as Chelsea exploited a disagreement between the teenager and manager Pep Guardiola over his immediate career path to complete a deal that could be worth up to 42.5 million.

The story is simple: Palmer wanted to go on loan and play, Guardiola told Palmer he either had to stay or find a new club. Fearing a season on the bench, Palmer opted to leave. Suddenly, a player born in Wythenshawe, south Manchester, who once had no particular desire to stray too far from home, found himself in London far from family and friends, having traded the treble winners for a Chelsea team in a state of flux with a new manager and more than 1 billion spent on players across the previous three windows.

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Palmer returns to the Etihad for the first time this weekend, having exceeded all expectations in the intervening six months. Guardiola's side have powered on without him to manoeuvre into a position where successfully defending the treble is becoming a tangible possibility. But Palmer has a chance on Saturday to derail that bid and make a point to Guardiola that he misjudged his talent all along.

Palmer's move to Chelsea was a real sliding doors moment for all concerned.

As part of the Blues' aggressive push to acquire the majority of Europe's finest young talent, they pursued a deal for Crystal Palace winger Michael Olise. It appeared straightforward: Olise had a 35m release clause, which Chelsea activated around Aug. 15, and with personal terms not expected to be an issue, there was widespread confidence the transfer would be completed. However, Palace moved swiftly to insist a new contract was already in place with Olise that removed the 35m release clause. The new terms have never been officially confirmed, but sources suggest they include a clause worth between 50m-60m, which would become active in a future transfer window.

Palace chairman Steve Parish posted a picture on social media of Olise signing his new four-year contract and, suddenly, Chelsea were left scrambling for alternatives.

Palmer had been on the Blues' radar after playing a key role in England's triumph at the European Under-21 Championships earlier that summer, and he appeared set for a bright future at Etihad Stadium. But by Aug. 17, Guardiola was publicly admitting the youngster could depart.

Palmer made just seven starts in City's 2022-23 campaign and after his eye-catching cameo against Arsenal at Wembley, he then capped another fine display with the equalising goal against Sevilla in the UEFA Super Cup match they would win on penalties.

"The opinion I had is he wanted to leave, but now I don't know what's going to happen," the City boss said after that game. "I don't think a loan is going to happen. He's going to stay or leave, but I think a loan is not going to happen."

It has since emerged that a loan was Palmer's preference. Reflecting on the move to Chelsea during a January interview with Sky Sports, Palmer said: "My thing was never to leave City. That was not my intention [to leave]. I wanted to go on loan for a year, come back and be ready for the first team but he [Guardiola] said I can't go on loan. You either 'stay or you get sold.'"

Guardiola's version of that conversation added the caveat that, with Riyad Mahrez's departure to Saudi Arabia, Palmer was told explicitly that he would get more game time. Palmer has a genuine affection for City -- he once played two games in the same day for them, first for the U23s and then for the senior team -- but he was unconvinced that enough opportunities lay ahead.

City did not plan for his departure last summer, but Chelsea's offer was remarkable: 40m up front for a player with great potential, but precious little evidence, with just 41 senior appearances, that he would succeed at the highest level. The structure of the deal and Palmer's status as a homegrown talent meant the fee could be banked as pure profit and aid in City's Financial Fair Play compliance. In anticipation of the move, City agreed a 55.5m deal to sign Belgium winger Jérémy Doku to ensure they were not left short in wide areas.

And so Palmer joined Chelsea on deadline day, Sept. 1, becoming the club's 13th summer signing, and agreed a seven-year contract with an option for an eighth season. Suddenly, he found himself living away from his parents in a new city, at a new club with a new manager attempting to establish himself in a squad thrown together at unprecedented expense.

"I wanted to just get in the team, play and show what I could do," Palmer said last month. "But to get in the [Chelsea] team straight away and hit the ground running, it has surprised me."

He's not the only one. Naturally left-footed with an ability to play wide or through the middle, Palmer has been a shining light during a difficult season at Stamford Bridge, operating with a freedom and poise largely unmatched by his teammates. The 21-year-old has registered 12 goals and nine assists across all competitions and became the 1,276th player to represent England men's senior team in November when making substitute appearances against Malta at Wembley and away to North Macedonia.

A closer look at his numbers in the Premier League further underlines Palmer's influence. He is sixth in the division for combined goals and assists (16) behind Liverpool's Mohamed Salah (22), Aston Villa's Ollie Watkins (21), City's Erling Haaland (21), Tottenham's Son Heung-Min (18) and Arsenal's Bukayo Saka (17).

Palmer's 10 goals have come from just 48 shots, the lowest figure in that top six by some distance; Son has scored his 12 goals from 52 shots, but Haaland (16 from 67), Salah (14 from 65), Watkins 11 from 71) and Saka (10 from 68) are much higher. That is chiefly due to half of Palmer's league goals coming from penalties -- only Salah (six) has scored more -- but that in itself is a demonstration of the level of responsibility he craved when deciding whether to leave City. One of those five successful conversions came against City in November, netting under maximum pressure in stoppage time at the climax of a breathless Premier League classic to secure a 4-4 draw against his former side.

Only Arsenal's Martin Ødegaard and Manchester United's Bruno Fernandes have attempted more through balls than Palmer this season (tied on 19 with Liverpool's Trent Alexander-Arnold and West Ham's Lucas Paquetá). And what about that precious game time he coveted? Palmer has amassed 1,506 minutes in the league this season. Compared with his former City teammates in wide positions -- Jack Grealish (703), Phil Foden (1,863), Bernardo Silva (1,511) and Doku (975) -- Mauricio Pochettino clearly trusts Palmer as Guardiola trusts his key wingers.

The big difference, of course, is league position. City have absorbed Palmer's exit to stay on course for back-to-back trebles while Chelsea are languishing in 10th place, 20 points off the leaders albeit with a chance to win the first major domestic trophy of the season against Liverpool in the EFL Cup final later this month. City may come to rue Palmer thriving elsewhere, but then again, they've become such a juggernaut under Guardiola that the departures of other seemingly important figures -- think João Cancelo, Leroy Sané and Gabriel Jesus, to name three -- have failed to derail them.

Meanwhile, Palmer and Chelsea would be insulted by any suggestion that he's taken a step down collectively in order to take a step forward individually. Chelsea still believe their policy of amassing top, young talent on long-term contracts will leave them well placed to compete with English football's finest for years to come. Palmer is emerging as the best example of that process, proof of Pochettino's ongoing ability to nurture precocious talent and mitigation of criticism that Chelsea's transfer strategy was too scattergun to succeed.

What they need, according to Pochettino, is positive experiences to grow together as a team. Finding a way to stop City's title charge this weekend would fit the bill.