"I've brought him in to nudge the strikers and to see if he can get a contract," Southend boss Phil Brown told BBC Essex.
"Mamady has been on my radar for a number of years. He's always impressed me with his mentality and attitude. He's not prolific in terms of goal-scoring, but he does affect the game."
Mali international Sidibe, who is 6ft 4ins tall, played 30 minutes in a development game this week.
"He's ring-rusty by his own admission. He's been in the wilderness, no-man's land. We'll see what the situation is on Friday," Brown added.
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