Palmer, a 23-year-old playmaker, watched from the sidelines as Chelsea secured a convincing victory with goals from Joao Pedro, Pedro Neto, Enzo Fernandez, Moises Caicedo, and Trevoh Chalobah.
Initially named in the starting lineup, Palmer was replaced by Estevao just before the game, and Maresca later confirmed that the England international had sustained an injury.
Maresca explained that Palmer had been struggling with a groin issue in the days leading up to the match and had attempted to play through the pain during the warm-up but ultimately decided not to risk further injury.
Maresca stated that the extent of the injury would be assessed, and Palmer's availability for future games would depend on the severity of the groin issue.