Palace only announced late last week that Sow had been added to their squad after impressing in preseason trials.
"Shortly after I signed my contract, I injured a ligament in the knee so right now I'm hurt, that's why the club did not introduce myself before. I'm not back until December or January.
"Then, it may be that I will be loaned for one or two months in January," Sow told Fotbolltransfers.com.
The Swede has signed a 12-month deal with Palace.
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