AVELEY halted Potters Bar Town's pursuit of an automatic promotion place, while Tilbury played out a goalless draw and Thurrock suffered defeat on the road.
James Webster's Aveley secured a 1-0 win over Potters Bar thanks to an early goal from Ryan Cosson.
The only goal of the game came with just eight minutes on the clock, as George Doyle's corner allowed Cosson to find the back of the net.
Striker Michael Murray passed up two good opportunities for the hosts, who were looking to close the gap on the Isthmian North's top two.
Rhys Madden then denied Lee O'Leary, who had been put through on goal.
Alex Teniola came close to doubling the Millers' lead four minutes after the break, but his dink over goalkeeper Berkley Laurencin fell just wide of the target.
Doyle was dismissed with more than 20 minutes still to play after headbutting a Potters Bar player, but Aveley held on with 10 men to pick up a valuable three points.
Meanwhile, Mark Stimson's Thurrock lost 2-0 to Harrow Borough in the Isthmian Premier League.
Fleet went into the game after being dealt with the blow of losing Joe Christou to East Thurrock United on Friday.
But the visitors held their own in the first half and went in at the interval on level terms.
Melvin Minter, the home goalkeeper, made a number of impressive saves to keep Thurrock at bay.
But a second half brace from Kurtis Cumberbatch proved to be the difference between the two sides.
Elsewhere, Tilbury were held to a goalless draw by AFC Sudbury.
The Dockers could not find a way past visiting goalkeeper Paul Walker, who pulled off fine saves to preserve a clean sheet at Chadfields.
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