Chelsea coach Maresca said at the press conference that Jackson will not be included in the roster and players may transfer.
Maresca said: "Jackson meets the playing conditions, but he is not going to be part of the squad. We have two centers, both of which are centers, and something may happen before the transfer window is closed."
Speaking of Jackson and Nkunku's future, Maresca added: "I think it would be better if they could find a solution, because they would be happier, and so is the club."
Jackson is 24, and has played 81 times since joining Chelsea, contributing 30 goals and 12 assists. Jacksonde's current turnover price is 50 million euros.
According to previous reports, many teams are interested in introducing Jackson, and Chelsea's price for players exceeds 60 million pounds.
