Liam Rosenior made a mess, cleaned it up and left Naples praying that Cole Palmer’s injury woes are over. All over the place during a wretched first half, an inspired comeback had Chelsea celebrating at full time. They had looked to Palmer for inspiration and, although the attacker was kept in reserve until the second half, he did enough during his time on the pitch to show why Chelsea have responded to suggestions that their main man is pining for a return to Manchester by branding him untouchable.

It was a cutting cameo from the player whose virtuoso brilliance downed Paris Saint-Germain in the Club World Cup final last summer. Introduced with Chelsea 2-1 down against Napoli and staring at the prospect of a two-leg playoff to reach the last 16 of the Champions League, Palmer was minimalistic but impactful. The 23-year-old’s presence alone was enough to restore order and, even if he is still not in peak condition, his first assists of a season disrupted by an array of niggles were a reminder of what Chelsea have been missing while their best player has been recovering from nagging groin and thigh complaints.

Palmer’s cameo was notable for its poise, calm and accuracy. He was involved when Chelsea pulled it back to 2-2, drifting in from the right to tee up João Pedro for a ­barnstorming equaliser.

Napoli, who needed a win to avoid a humiliating early exit, were stung. They left themselves open as they chased a third goal and were caught out again when Palmer slid a beautiful pass through to João Pedro, whose second goal of the night ensured that Chelsea finished the league phase in sixth place.

It was not straightforward. For Antonio Conte, though, Napoli’s elimination was a continuation of his dreadful European record. The Italian champions tired in the second half and Conte, the last manager to lead Chelsea to the Premier League title, had no way of responding when Rosenior made a series of smart alterations.

Rosenior had bungled his starting lineup. He matched Conte’s 3-4-2-1 system and explained that he wanted to go man for man but Chelsea were confused before half-time. Wesley Fofana was the only recognised centre-back in the team – a curious decision given that Rosenior had four defenders on the bench – there was plenty of space behind Chelsea’s wing-backs during the first half.

Pedro Neto and Malo Gusto struggled. Behind when Juan Jesus handled a Reece James free-kick and Enzo Fernández put Chelsea in front from the spot in the 19th ­minute, Napoli responded in style. They swept forward and equalised through a fine solo goal from Antonio ­Vergara, who held off a challenge from Moisés Caicedo and turned beyond Fofana before driving a low shot past Robert Sánchez.

It was Napoli’s first goal from open play in the competition this season. Conte had said they were in a state of emergency because of their injury problems. They have lacked creativity without Kevin De Bruyne, absent since October with a torn hamstring, but they repeatedly picked Chelsea apart. Scott McTominay was dominant in midfield and was not the only former Manchester United player who caught the eye. Rasmus Højlund was also in the mood and put Napoli in front when he darted beyond Fofana to turn Mathias ­Olivera’s cross in from close range.

Chelsea were arguing among themselves when the first half ended. Rosenior responded by replacing Neto with Palmer. Napoli sat back in an attempt to protect their lead. There was a lot of possession for Chelsea at the start of the second half but the challenge was making it count in the final third.

There was no sign of an improvement from the visitors as the hour approached. It felt as if Rosenior was owning up to a tactical error when he removed Gusto for Trevoh Chalobah, who moved alongside Fofana in ­central defence. Jamie Gittens was also introduced on the left. Andrey Santos, the young Brazilian, made way in midfield. The setup felt more conventional. Estêvão moved to No 10, ­Fernández dropped next to Caicedo in midfield and Chelsea found their flow. Palmer stirred. His flick found João Pedro and the ­forward drew Chelsea level by ripping an ­outrageous shot past Alex Meret from 25 yards.

The goal meant Napoli were on their way out. They had to push again. Romelu Lukaku, just back from a long-term injury, came on to face his old side. Yet Chelsea would not be haunted by their past.

They waited for Napoli to commit players forward. Their patience was rewarded when Palmer released João Pedro, who raced away, swerved right and ­finished emphatically.

Sánchez denied Lukaku a late equaliser. Napoli were beaten at home for the first time since December 2024.

Chelsea, with their first away win at this level since October 2022, had silenced some of the noise about their inexperience.