Grays, who can't buy a win in the Nationwide Conference, continued their love affair with the FA Trophy with an emphatic win against Kent neighbours Welling United on Sunday.
The Conference South side took the lead after just six minutes but Grays drew level by half time and, after a torrential cloudburst in the early stages of the second half rained in goals.
The final nail came from Stuart Thurgood, making his first start since January 20. He has lifted the trophy for Blues in the last two seasons and he was joined on the score sheet by John Martin and Glenn Poole, who have also picked up winners' medals with Grays.
They netted after Millwall loanee Gavin Grant had fired Grays back into this quarter-final tie with a 30 yard strike on 34 minutes, though home keeper Paul Hyde perhaps ought to have done better in trying to keep the shot out.
That ruled out the sixth minute opener from Wings' Moore, who headed home after Jamie Day had crossed into the box and the ball was headed back into the danger area by Danny Kedwell.
The early stages of thee second half were played out in a rainstorm and the pitch began to cut up heavily.
However, Grays revelled in the mud and they went ahead with Poole's header on 72 minutes.
Welling pushed forward seeking an equaliser but were caught out when John Martin headed a third on 76 and the Grays contingent in a crowd of 1.163 were sent home deliriously happy when Thurgood marked his comeback game with the fourth goal four minutes from time.
Grays now join fellow Conference sides Stevenage, managed by former boss Mark Stimson - the man who led them to their two Trophy triumphs, Northwich Victoria and Kidderminster Harriers. The semi-final draw is on Monday.
Thanks to the Thurrock Gazette for the report