Currently just eight points is the difference between Crewe in second spot and 13th-placed Bromley.
Five points split Crewe and Grimsby in 9th with all to play for in the second half of the season.
Spireites have dropped off the pace over Christmas following three defeats in a row and find themselves six points off the pace.
Here we look at the latest promotion odds currently on offer with league sponsors SkyBet, running from least likely to most likely.
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