The England international is a huge loss to The Blues who managed without him in their 5-1 victory over relegation candidates West Ham United last Friday. Reports state that he will now have a scan on his groin this coming Tuesday to determine the full extent of any issue.
The midfielder was spotted holding his groin minutes before kick-off, and was quickly escorted to the dressing room with a member of Chelsea's backroom staff who monitored him behind the scenes.
Speaking after the win over the Hammers, Maresca indicated that Palmer had been struggling with his fitness throughout the week leading up to the fixture.
"Cole, in the last four or five days, was not 100%. Today, he tried to warm up, but he felt something," the Italian revealed.
"So, we prefer not to take any risk to get worse, and we'll see now in the next hours if it's something important or not. Probably (for the) Palace game he was not 100%.
"But he is trying to make a big effort for the club, for the team, for the fans. Because he is really keen about the team. Tonight, again, he tried again. But it was not very good."
Standard Sport reports that Chelsea’s medical team will now assess the 23-year-old, but he did not train with the squad on Tuesday. This will be a worry for the side that hosts Fulham in the Saturday lunchtime kick-off and will need all the firepower they can get.