Dennis Oli was the hero for Grays as he came off the bench to grab the only goal of the game against Crawley.
Michael Kightly went close for the hosts early on but saw his well-struck volley and header go wide of the goal.
A double substitution at half-time paid dividends for Grays with Jamie Slabber and Brett Johnson being replaced by Oli and Cam Mawer.
And Oli was immediately in the thick of things as he collected a Kightly pass to rifle home the winner on 69 minutes.
Grays Athletic: Bayes, Sambrook, Hanson, Johnson (Mawer 45), Nutter, Kightly, Thurgood, Williamson, Martin (Poole 78), Slabber (Oli 45), McLean.
Subs Not Used: Eyre, Battersby.
Goals: Oli 70.
Crawley Town: Smith, Simpemba (Wormull 84), Mendy, Woozley, Judge, Armstrong, Blackburn (Ekoku 77), Jenkins (Coleman 77), Opinel, Scully, Clare.
Subs Not Used: Ward, Giles.
Ref: S Crighton (Woodley).