He missed last weekend's FA Cup defeat at Brighton, although boss Maresca claimed beforehand that the problem was not too bad.
After the recent FA Cup clash with the Seagulls, Maresca admitted that Jackson's absence severely hampered his team.
ENZO MARESCA has been dealt a blow with Nicolas Jackson ruled out for around six weeks.
Fellow striker Marc Guiu is also out for some time with a muscle problem, leaving Maresca facing a crisis up front.
But a scan this week has shown it to be more serious than first thought and nine-goal Jackson now faces a spell on the sidelines.
