The Finn underwent surgery on his left wrist in late June and despite initially progressing well, he has begun to experience discomfort.

Investigations revealed further damage to the wrist, and as a result the former Southampton man will have more surgery next week to repair the problem.

Niemi told www.fulhamfc.com: "I'm extremely disappointed that having returned to training, I now have to undergo further surgery.

"However, I'm confident that I can recover from this setback sooner rather than later.

"I was looking forward to joining the new players who have been added to the squad but I will now focus on my rehabilitation after surgery and look forward to returning as soon as possible."