BLUES skipper George Horan clinched a last gasp winner in a thrilling contest at Gigg Lane.
Blues striker Chris Simm had put Chester 1-0 up after just two minutes when he headed home a right-sided corner from Matty McGinn.
But United equalised in the 32nd minute when Carlos Roca converted a penalty after Ben Deegan had been fouled by Alex Brown.
And Roca celebrated a spectaular 25 yard free kick to earn United a 2-1 lead after 37 minutes.
Chester created numerous chances after the break before and after United had been reduced to 10 men following Adam Jones' dismissal for two bookable offences in the 62nd minute.
Simm put Chester back on level terms in the 79th minute when he tapped home after seeing Spencer parry a George Horan header from Wes Baynes' pinpoint cross.
Horan clinched Chester's third goal in the 90th minute after United had failed to clear Baynes' right wing cross.
FC UNITED OF MANCHESTER (4-4-2): Spencer; Jacobs, Neville, Cottrell, Jones; Stott, Roca (Chadwick 63), Carr, Deegan (Mulholland 82); Norton, Wolfenden. Subs (not used): Platt, Battersby, Grimshaw.
CHESTER (4-4-2): Danby; Brownhill (Baynes 57), Horan, Taylor, McGinn; Booth (Wilde 67), Brown, Powell, Howard; Simm, McNeil (Rainford 67). Subs (not used): Ormrod, Judge.
REFEREE: David Midgley (Huddersfield).