With Luke Marshall unavailable, Jake Larkins injured and Lee Flynn rested, Grays made three changes to the team that won away at Cheshunt on Tuesday, bringing in Jake Hall, George Kamurasi and Danny Bunce respectively.
Grays started the game the better of the two teams and crated a couple of early chances.
In the 8th minute, Harry Agombar found space on the edge of Tilbury area, cutting inside on his right foot but his curling shot went narrowly over the crossbar.
Agombar again came close in the 12th minute as he collected the ball on the left wing, worked his way into the area but his curling shot again went narrowly over the bar.
Tilbury were forced into an early substitution as ex-Grays player Emile Aiken injured his shoulder and was unable to continue, being replaced by Martin Llewellyn.
Both teams were clearly ready for a fierce and physical contest as neither yielded in every challenge, a classic derby encounter.
Jack Carlile was shown a yellow card in the 25th minute as Joao Carlos showed quick feet to move through the Tilbury midfield before being hacked down before he could advance on the Tilbury defence.
Grays deservedly took the lead in the 31st minute as Agombar collected the ball on the left and fired a low curling pass down the line with the outside of his foot which was picked up by Jake Hall. He cut inside two Tilbury defenders to give himself a yard of space before firing an unstoppable shot off the crossbar and into the corner of the net.
The final chance of the first half came to Leon Lalite two minutes later as he collected a knock down on the edge of the area but his effort was easily saved by James Marrable in the Tilbury goal.
During the interval Paul King was replaced by Jake Pooley for Tilbury, who took a knock in the first half following a robust challenge by Jack West.
Tilbury changed formation in the second half, dropping Joel Barnett into midfield to match Grays 4-5-1 formation.
The home side looked more dangerous at the start of the second half and put Grays under plenty of early pressure, forcing several corners in the first fifteen minutes which Grays managed to deal with.
Grays almost doubled their lead on the hour mark as good play between Agombar and West lead to the ball being rolled into the path of Hall on the edge of the area. His low shot was goal bound until Marrable made a good diving save to clear the danger.
Jack West picked up a yellow card a minute later following an innocuous challenge for persistent fouling.
Tilbury registered their first real attempt on target of the game in the 64th minute as a long free kick was played into the area and the ball dropped to Danny Francis but his tame effort was comfortably saved by Kamurasi at the near post.
The biggest talking point of the game came in the 70th minute as both teams were reduced to ten men following a melee in the middle of the park.
Firstly Danny Bunce went into a tackle strongly, sliding along the ground and just catching the played with his leading leg. The referee blew for a foul just as Joel Barnett went face to face with Bunce which started the pushing and shoving. After the referee eventually calmed the players down, both Bunce and Barnett were shown a red card for their roles in starting the incident.
Grays immediately responded by replacing Harry Agombar with Lee Flynn to get the Grays back line back to full strength.
The away side continued to create chances and in the 75th minute Carlos found himself unmarked at the back post with the ball but his shot was well saved by the feet on Marrable to keep the score at one-nil.
On 78 minutes Grays made their second substitution, replacing Jack West with Joe Sweeney.
Grays almost put the result beyond doubt in the 87th minute as Hall crossed to Carlos at the back post but his shot was again saved and cleared.
As the game entered injury time, Grays made their final substitution as man of the match Jake Hall made way for James Bunn.
Grays saw off the five minutes of injury time as Joe Sweeney and James Bunn linked well to help run down the clock deep in the Tilbury half.
The final whistle was greeted by raptures of applause from the away fans and you could see the result meant a lot to the players and they celebrated on the pitch.
Grays next fixture is on Tuesday night, as they host Waltham Forest at Rush Green in the 2nd round of the Isthmian League Cup before returning to league action next Saturday at home to Harlow Town.
Grays Athletic: George Kamurasi, Craig Pope, Ryan Kirby, Junior Baker, Danny Bunce, Joao Carlos, Leon Lalite, Kenny Beaney, Jake Hall (James Bunn 90), Harry Agombar (Lee Flynn 73), Jack West (Joe Sweeney 78)
Unused Subs: Grant Cooper, Tyrone Scarlett