Kyle Wootton scored deep into second-half stoppage time to earn us our third consecutive victory and end Sutton's winning start to the season.
Chances were few and far between for both sides but we certainly shaded things with Jake Reeves, Enzio Boldewijn and Wootton all having opportunities to score earlier in the match.
But, with seconds left on the clock, Wootton was on hand to score his fourth goal of the season in scrappy style to take us back up the M1 in jubilant spirits.
Neal Ardley made three changes to the side that beat Barnet 4-2 at the weekend.
Cal Roberts, who had been suffering from fatigue in the build-up, joined Sam Graham and Damien McCrory in dropping to the bench, while Alex Lacey, Jim O'Brien and Richard Brindley stepped in.
That meant we lined up in a 4-3-3 formation with Ruben Rodrigues, Wootton and Boldewijn leading the line.
But it was central midfielder Reeves who had a good chance to give us the lead inside the opening two minutes when Dion Kelly-Evans' low cross skidded through to him. He could only send his first-time effort over from inside the area.
We had another opportunity to break the deadlock on 21 minutes when the ball bounced to Boldewijn in the box but the Dutchman didn't strike it cleanly, bouncing it into the turf and dropping it on to the top of the crossbar.
Other than a speculative Richard Brindley shot which fizzed a couple of yards wide of the post, that proved to be the final goalmouth action of a cagey half played on a rain-drenched artificial surface.
The second half continued in cagey fashion and we had to wait until the hour mark for our next sniff of goal, Reeves threading a delightful through ball for Boldewijn only for Ben Wyatt to make an outstanding covering challenge to turn it behind for a corner. Lacey nodded the ball over from the resultant set piece.
Slocombe was called into action for the first time moments later, Tobi Sho-Silva spinning in the area and firing the ball straight at him.
Ardley's first change came with 20 minutes to play as Roberts replaced Rodrigues, with Jimmy Knowles coming on for Enzio Boldewijn shortly afterwards.
But despite those attacking changes we had to wait until the 87th minute to next break down our hosts as O'Brien did brilliantly to release Wootton into the area only for Dean Bouzanis to stand firm at his near post to make a strong save.
Wootton then latched on to a brilliant O'Brien free-kick but failed to keep his header down inside three minutes of added time.
It looked like the game was destined for deadlock but in the dying embers Doyle controlled Bouzanis' failed clearance and played the ball to Knowles, who saw his shot saved. But the ball came to Wootton in the area and the in-form forward made no mistake, winning us the game with seconds to go.