James has been plagued with injuries over the past two campaigns, making just 16 Premier League appearances in the 2022-23 season, and playing just 413 minutes last term.
Ahead of Chelsea's lunchtime kick-off with West Ham on Saturday, Maresca said that James - who was appointed as club captain in August 2023 - still doesn't have a return date.
When asked about the 24-year-old, Maresca said: 'His injury is a bit delayed.
'The most important thing is players come back when they are 100% fit. Reece is still out. Unfortunately, we don't have an idea at the moment [when he’ll be back]. In this case, he’s been very unlucky.”
James picked up the current injury this summer after a prolonged spell on the sidelines recovering from hamstring surgery in December 2023.
He did make two cameo appearances back in May totalling 30 minutes, but his injury issues meant he was never in the race to make the Euro 2024 squad with England.
James had featured for Chelsea during their summer tour of the USA but is yet to feature for the London club in the Premier League so far this season.
The 24-year-old fullback has suffered a torrid time with hamstring injuries throughout his career, which has undoubtedly prevented him from achieving the full potential of his prodigious talent as yet.
James had confidence that his fortunes would turn around in the summer of 2023 as he posted a picture of himself on X, with the caption: 'New era loading... ps. We just getting started.'
James has started 118 games across all competitions in his Blues career, with 81 of those coming in the Premier League.
His problems in the professional ranks started after an ankle injury while playing for England at the Toulon Tournament in June 2019.
James (top left) had to watch on for the majority of last season playing just 413 Premier League minutes
Since then, James has been sidelined with knee, thigh, and ankle problems, with his hamstrings a particular area of concern.
As well as missing Euro 2024, he was also absent from the 2022 World Cup squad after suffering a knee injury in the build-up.
Malo Gusto has impressed in the absence of the club captain, though Chelsea will be short of right-backs when they face West Ham.
Gusto will not be available for the short trip across the capital after he was ruled out of their win at Bournemouth last week, after suffering a thigh injury against Crystal Palace earlier this month.