Both Nkunku and Jackson signed for Chelsea in 2023, but have seen their opportunities limited by the arrivals of summer signings Joao Pedro, from Brighton, and Ipswich’s Liam Delap.

Joao Pedro, 23, scored three goals for Chelsea at the Club World Cup and got off the mark in the Premier League with a goal in their 5-1 win at West Ham on Friday.

Delap, 22, also got on the scoresheet in the summer’s Club World Cup and has featured in Chelsea’s opening three games of the league season, but pulled up feeling his hamstring in Saturday’s match at home to Fulham and was immediately substituted.

Jackson was a regular in the starting line-up in his two seasons at Chelsea, but has not played for the club since a substitute appearance in their semi-final victory over Fluminense in the Club World Cup in July.

The former Villarreal forward has a solid scoring record of 24 goals from 65 Premier League appearances.

But he has under-performed his expected goals total by seven over the past two years, the second-most of any player in the top flight.

A key factor has been his record in what Opta define as ‘big chances’.

Jackson has scored just 18 of 61 such opportunities (29%), a relatively low conversion rate compared to other top forwards.

He was an unused substitute in Chelsea’s victory over Paris St-Germain in the Club World Cup final and did not figure in either of their opening league games – a goalless draw at home to Crystal Palace and 5-1 victory at West Ham.

Chelsea went into Saturday’s early game at home to west London rivals Fulham fourth in the table, on four points.