United made their first ever trip to Gander Green Lane to face newly promoted Sutton United.
Chris Beech made two changes to the side that earned a 2-2 home draw against Scunthorpe United last, with Lewis Alessandra and Brennan Dickenson back into the fold.
Tristan Abrahams missed out through a training ground injury with Zach Clough taking a place on the bench.
The hosts had the lead with just three minutes on the clock when Ajiboye used Bennett to create space. The wide man employed pace off the striker's touch, as he bent his run into the area, and he feinted to cross to shrug off his marker before then sending it hard at the near post. Donovan Wilson had followed the move and he managed to bundle it over the line from close range.
United had half a sight from the restart when Alessandra pulled into space, but his low shot was straight at Bouzanis.
Sutton earned a free kick on the edge of the box when they sent the ball long moment laters, and Milsom took charge as he tried to get it under the wall. Mellish got a boot on it and it was cleared.
The visitors tried to rally and a long throw from Riley pinged around in front of Alessandra and Mellish, but the U's broke and Boldewijn strode past Mellor. His cross was cut out, but play was spread to Ajiboye on the right flank and a fierce drive from him rattled the outside of the post.
Left back Jack Armer won a free kick tight by the touchline after he'd gone on a sprint, and Guy's delivery needed a claw from Bouzanis as it threatened to dip beneath the bar. Alessandra recycled it, but it was sent to safety before McDonald could put a head to it.
The home side were a whisker away from a second strike on 16 minutes when Milsom whipped a free kick from wide to the far post. Bennett was there with the header but he somehow only managed to find the side netting, with Norman committed and stranded off his line.
Another Riley long throw was met on the volley by McDonald, after a weak clearance from John dropped in front of him. He had half a shout for a penalty as it smacked into an arm. Mellish put the loose ball back across the face of the area, as did Dickenson when Eastmond hooked it to him. Both deliveries missed their mark.
Carlisle fashioned another good move when Gibson pulled wide for a through ball from Alessandra. His cut back was met by Mellish but Bouzanis was down smartly to touch the ball around the post. McDonald jumped highest for the corner, but his header rose skywards from the off.
Wilson tried to add a second just after the hour when a diagonal pass was clipped into his path. He opted to shoot early as he entered the box and it was always arrowing wide.
Alessandra twisted and spun his way past two challenges as he came in from the left wing, and Dickenson took over with a snapshot on the turn. Bouzanis was well positioned again.
Trickery from Ajiboye saw him bully his way to a punt as Sutton came again, and that was a warning shot across the bows as Wilson calmly fed a rolled pass into the path of Alistair Smith, when the ball was turned over in midfield. A crisp, accurate connection took the ball past the dive from Norman and into the bottom corner.
The Cumbrians should have got something just before the break when a Burst from Guy saw him get it to Mellish. A quick touch from him invited Dickenson to cross, and the first time teaser of a swipe whisked invitingly across the face of the target. Alessandra and Mellish were there but neither could make contact.
But it was Sutton who were left with their heads in their hands when an added time corner found Kizzi unmarked and with the target to aim at. He fluffed his lines, and the loose ball was cleared before Bennett could pounce.
Carlisle had an early corner at the start of the second period and Whelan challenged as it came his way. It dropped to Alessandra, but he was under pressure and the volley spun high off his toe.
Superb skill from Mellish followed in the next attack as he touched the ball three times to take defenders out of the game. He suddenly had just the stopper to beat, but Bouzanis was equal to it as he threw himself down to make a two-handed save.
Norman was needed on 54 minutes when Ajiboye broke from inside his own box from a cleared Guy corner. A thunderbolt was top corner bound until a strong hand got in the way.
A flurry of yellow cards were awarded on 56 minutes as Mampala announced his arrival with a hefty challenge. Dickenson and Goodliffe were reprimanded for the part they played in the aftermath.
Norman was at full length again when a ricochet off Whelan from a Milsom cross on the run spooned into the air. Wilson waited an age for it to come his way and his 12-yard volley was bang in line. A block and a quick recovery from the keeper kept the nets untroubled.
The resulting corner went very deep, and Kizzi cushioned it as he picked out Smith. He was frustrated with himself when he popped his close range header over the bar.
Substitute Brad Young had an effort on the turn when Mellish found him unmarked, after he'd gone on a typical surge, but Bouzanis was able to watch it all the way as a defensive boot took the sting out of it.
Sutton bagged their third with 20 minutes left to play when Olaofe came out of a tussle with Whelan with the ball at his feet. He waited for support, and that came through Alistair Smith when he called for the pass. A firm cruncher whistled into the bottom corner as he kept his eye on his strike.
The afternoon got worse for the visitors when Mampala clashed with Kizzi as they both went for a high ball, and the referee deemed it to be a bookable contact as he sent the substitute from the field of play.
Zach Clough came on for the last 15 minutes and his first contribution was to pick out Alessandra in a congested penalty area. The striker put his boot on it but Goodliffe did enough to take it away from the target.
The nippy David Ajiboye rubbed salt into the wounds when he unexpectedly found himself with just Norman to beat, having initially dabbed hopefully at a through ball. He bided his time before putting it away.
Sutton wanted a penalty when Olaofe went down as he came up against Whelan, but Carllisle kept their concentration to then deal with the second wave.
What appeared to be a first goal for the club for Brad Young was chalked off for offside, as he volleyed from a Clough cross, and the same player had another attempt blocked after the ball had gone this way and that inside the box from a Guy corner.
Joe Riley put one into the hands of Dean Bouzanis in time added on, but it was the league new boys who celebrated their victory as the final whistle went.
Sutton United - Wilson (3), Smith (37, 70), Ajiboye (81)
Sutton United - Goodliffe (56)
Carlisle United - Mampala (56 & 71 - sent off), Dickenson (56)
Sutton United - Bouzanis, Goodliffe (Rowe 81), John, Ajiboye, Eastmond (c), Boldewijn, Kizzi, Milsom, Wilson (Olaofe 66), Bennett (Bugiel 80), Smith. Subs - Chalupniczak (gk), Wyatt, Beautyman, Randall.
Carlisle United - Norman, Mellor (Mampala 53), Whelan, McDonald, Armer (Young 62), Mellish, Guy (c), Riley, Gibson (Clough 76), Alessandra, Dickenson. Subs - Jensen (gk), Devine, Charters, Feeney.
Referee - Simon Mather
Assistant Referee 1 - Joseph Stokes
Assistant Referee 2 - Paul Kelly
Fourth Official - Mark Derrien
Observer - David Crick
Attendance - 2,873 (480)