Gravesend overcame 10-man Margate in their Kent derby at Crabble.
Darren Watson had put Gate ahead after he was set up by Jake Leberl, but Chris Moore headed in Lee Protheroe's corner to level in first-half stoppage time.
Rob Haworth's 52nd-minute header then put Fleet in the lead, and Ben Abbey made it 3-1 with a long-range strike.
Margate's defeat was sealed when Sam Sodje was sent off for violent conduct after clashing with Steve McKimm.
Margate: Smith, Sodje, Edwards, Porter, Annon, Oates, Saunders,
Leberl, Piper, Watson, Keister. Subs: Mitten, Zoricich, Sigere,
Stadhart, Clarke.
Gravesend: Wilkerson, Protheroe, Duku, Moore, McClements, Owen,
McKimm, Drury, Walshe, Abbey, Haworth. Subs: O'Reilly, Shearer,
Gradley, Evans.
Referee: M Russell (St Albans)