Chesterfield's lead at the top of npower League Two was cut to six points after they went down to a shock 2-0 home defeat by Morecambe.
The loss, coupled with Wycombe's victory at Macclesfield, sees the Chairboys chip away at the Spireites' lead and they also have a game in hand.
Kevan Hurst, with a long-range effort, put the Shrimpers ahead before James Spencer secured the points with a firm shot into the top right-hand corner of the goal.
It was only Chesterfield's fifth league defeat of the season and their second in 15 league games. The surprise win moves Morecambe further away from the danger zone.
Gareth Ainsworth scored the only goal in Wycombe's victory in a game which saw three men sent off.
Macclesfield's Reneil Sappleton was sent off for a professional foul in injury time before team-mate Emile Sinclair and Dave Winfield of Wycombe were dismissed in the fourth minute of added time for violent conduct.
Two goals in the last two minutes saw Rotherham claim a 4-2 win at Burton to keep up the pressure on the top two.
Greg Pearson gave the hosts an ideal start with a second-minute goal before Johnny Mullins levelled.
Aaron Webster regained the lead for Burton before missing a penalty six minutes after half-time, something he was left to rue when the Millers levelled through Marcus Marshall.
The game was heading for a draw before Adam Le Fondre scored with a minute to go and Ryan Taylor wrapped things up. The defeat keeps Burton in the bottom two.
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