Lester received a straight red card in injury time at the end of the Spireites' 1-1 home draw against Burton last weekend and the eight-goal striker will begin a three-match suspension in Essex.
Fellow veteran forward Luis Boa Morte is manager Paul Cook's only other concern ahead of the game on Friday night.
Boa Morte missed the Burton match due to a hamstring problem and the former Portugal international remains a doubt.
Chesterfield will be looking to extend their unbeaten run to six league games knowing victory would temporarily move them up to sixth in the table above Southend, who are unbeaten in their last 12 matches in all competitions.
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- Luis Boa Morte