Monk has been absent for all of March so far and now looks destined to sit out the rest of the month minimum with his injury after it was initially hoped that he would miss just the one game – the victory at Huddersfield on March 1.
However, treatment on Monk's injury has not gone as well as all parties had hoped and the skipper must watch from the sidelines as his team mates carry on the promotion charge without him
"You have to be very careful with a back injury," said Swansea boss Roberto Martinez.
Dennis Lawrence is also a doubt for the trip to Southend with an ankle injury but the Swans manager is hopeful that he will make a full recover in time for Friday night's fixture.