Ben Harris saw an early penalty kick saved, which proved to be the Rebels’ best chance in a game of few openings.
Dan Roberts fashioned a chance for himself after stealing the ball from a defender, but his effort deflected over the bar.
But from the resulting corner, a handball offence was spotted by referee Steven Hughes, giving Ben Harris the chance to open the scoring. However, Rangers goalkeeper Chris Haigh got down quickly to keep out the striker’s firmly hit effort.
Concord went close shortly after, with Scott High drawing a good save from Jack Turner.
Max Worsfold had two chances to find the breakthrough midway through the first half, but the first was blocked and the second found its way harmlessly through to Haigh – and shortly after, Sam Togwell’s curling effort flew just past the upright.
Minutes later, Roberts created another chance for himself but Haigh denied the Rebels again.
Concord striker Joel Nouble hit the crossbar with eight minutes of the first half remaining in the hosts’ best chance to that point, after being teed up by Decarrey Sheriff.
The opening passages of the second half were tight, with both sides only looking likely to threaten from set-pieces, until the 65th minute when High fired narrowly over the bar after Lamar Reynolds was tackled on the right.
Slough needed Turner to come to the rescue just three minutes later as he pulled off a fine save to deny Reynolds after being played through one-on-one.
The Rebels would threaten the hosts’ goal just once more, thirteen minutes from time when Sam Togwell sent a header over the bar from a Warren Harris cross.
Concord could have settled the tie four minutes from time, but Kit Elliott fired over after being found by Nouble.
The two sides will play to a finish at Arbour Park on Tuesday evening, with a place in the First Round at stake.
Concord Rangers Lineup
Chris Haigh, Aron Pollock, David Olufemi (c), Scott High, Billy Roast, Jack Cawley, James Blanchfield, Kreshnic Krasniqi, Decarrey Sheriff (Kit Elliott 70), Lamar Reynolds (Marcel Barrington 86), Joel Nouble. Unused substitutes: Danny Green, Archie McFadden, Ben Search, Alex Hernandez, Daniel Howett.