Chelsea were warned against selling Nicolas Jackson to a direct rival this summer, but they went ahead with it anyway and could end up paying for it dearly come May.

The Senegal international is in rip-roaring form for his new club. Aston Villa have found their feet after a slow start - an annual tradition at this point - and so too has Jackson: he has scored seven goals since the start of September.

On Saturday, the 25-year-old bagged an impressive brace against league leaders Man City. Jackson opened the scoring just six minutes into the match after John McGinn pounced on a poor touch from Marc Guehi.

The striker showed a composure he often lacked at Chelsea when he tricked the onrushing Elliot Anderson with a simple fake shot before rifling the ball past Gianluigi Donnarumma into the roof of the net.

He doubled his tally in the 60th minute by finishing off a move he himself had started with a first-time effort from the edge of the box that Donnarumma should really have comfortably saved.

Chelsea sold their best player

Thanks to Jackson's goals, Villa ended Man City's perfect start to the season and reduced the gap to the top four to just two points. Fourth is currently occupied by the Senegalese's former club Chelsea, although they have yet to play.

The Blues haven't struggled to score goals under new manager Xabi Alonso this season, but there might be some regret over selling Jackson to Villa if the Birmingham club continue their strong form throughout the season.

After all, the two clubs are direct rivals for Champions League qualification and, depending on what happens with Man City's charges, they may even find themselves in a title race come the spring.

In the summer, FootballTransfers warned Chelsea that they were selling their best player without even realising it. Data from analytics firm SciSports ranked the 25-year-old as the club's most highly-rated star.

SciSports collects hundreds of in-game data points and uses them to calculate a skill rating. No player at Chelsea had a higher score than Jackson at the time, and that remains the case to this day despite the strong form of Morgan Rogers and Cole Palmer in these early stages of the season.

Jackson is the second-best centre-forward in the Premier League behind Erling Haaland, as per SciSports, whereas Joao Pedro only ranks eighth, albeit the Brazilian is rapidly developing.

Whether Pedro will actually catch his former teammate is doubtful, however, as Jackson is the same age and is believed to have a significantly higher ceiling. His immense potential was evident even during his time at Chelsea.

— Aston Villa (@AstonVilla) October 24, 2026

Despite being derided for his wastefulness in front of goal, the underlying numbers suggested that the Blues had an elite striker on their hands. Since 2020, basically only Haaland has been putting up more consistently strong attacking metrics than Jackson.

Instead of supporting him and helping him refine his game, Chelsea just gave up on him. They shipped him out on loan to Bayern last year, where he - understandably - failed to supplant Harry Kane. Vincent Kompany wanted to keep Jackson in Munich, but he was simply too expensive.

"The guy hasn't done anything wrong, he has trained extremely well, he won AFCON," the Bayern boss said. "When Harry Kane plays in your position, or Michael Olise, or Luis Diaz, it is a bit difficult. There is nothing more to it."

When Aston Villa signed Jackson for €56 million, it was seen as a solid bit of business from Chelsea. They turned a sizeable profit on a player they didn't want, and even more money could be coming their way via bonuses.

And yet, in today's market, with Julian Alvarez being touted for a €150m transfer, the deal could end up looking like a steal for Villa if Jackson keeps up his red-hot scoring form.

It is early days, of course, but Unai Emery seems to have - yet again - unlocked his former Villarreal protégé. What Chelsea failed to achieve in three years, the Basque has managed in a matter of months.

If Villa, spearheaded by Jackson, end up having a successful season, perhaps even at the expense of Chelsea, questions will be asked of the Blues' capacity to adequately judge players.