United went into their Easter fixture with Scunthorpe off the back of consecutive victories and clean sheets, and looking for more of the same with some solid recent performances under their belts.
Hard-to-beat Scunthorpe had lost just once in their previous eight outings, with a straight run of five games unbeaten to protect as they came to Brunton Park.
The squad of 18 was unchanged for a third time, with Aaron Hayden once more taking on captain's duties.
United kicked off, attacking the Waterworks End, and an overlap from Tanner earned an early throw. It was cleared back to Riley, but his inswinging delivery was cut out before Zanzala could get on the end of it. Mellish put his body in the way of the spooned connection from O'Malley, with the Blues keeping it alive, and he made sure Patrick had space to work a way past his man. The striker crossed on the run but it went high.
Scunthorpe won a corner on five minutes when Beestin tried to get past Riley. Gilliead sent it long but everyone had moved towards the near stick.
United came again when Mellish did well to control an awkward ball. The defenders backed off, and a reverse pass to Zanzala brought a touch on the stretch from him inside the six-yard area. Alessandra chased it, and it was hooked behind for a corner.
That delivery from Guy was excellent, and it caused all kinds of problems with Bedeau doing just enough to prevent Patrick from getting on the end of it, after Armer had tried to find a volley.
A second effective corner from Guy picked out Hayden, who had pulled off his markers and into acres of space. He popped his header back across the face of goal, and Armer was there once again. It came at him at speed and he could only guide his glance wide of the upright.
Another Riley throw bounced up for Hayden to strike as he lurked on the penalty spot, but it was blocked and it spun high. Meliish recycled it, and Riley spread it wide. A cut back from Mellish had Zanzala's name written all over it, but O'Malley checked his run and that allowed him to get a toe in the way.
An excellent Carlisle move saw Mellish steal possession deep inside his own half before setting off on a run. He used Patrick, who played a neat pass inside to Alessandra. Mellish had continued his sprint, and he didn't disappoint with a dinked cross. Zanzala was up to meet it but he was judged to have handled, before he could make the header, and despite having been nudged out of the path of the floating ball by a hefty shove.
Carlisle were close on 19 minutes when another ball into the area was contested by Zanzala. Clarke missed his kick as Zanzala tumbled, but the striker had the presence of mind to swivel on his hip as he aimed a boot at the ball. Watson was relieved when it skipped past his post.
Patrick turned O'Malley inside out on the half hour as he twisted one way, then the other, before sending it low. Bedeau cleared it and the moment was gone.
Scunthorpe made their first real chance of the night when a cross from Beestin was fed out to Karacan. O'Malley sprinted on, and he used the midfielder for a one-two which suddenly put him inside the box. He unleashed a low drive and Farman did well to dive full length and palm it away for a corner.
Gilliead placed it, and his flighted cross found Clarke, 10-yards out, with time to measure his header. It needed another solid two-handed intervention from Farman as it angled at his nets.
The Blues had a corner in time added on for the half as Zanzala invited Mellish to cross. Guy found Hayden once again, as the defender curved his way into space, but Loft put his goalbound header over the bar with the slightest of touches. Hayden was first to the next delivery, but the home side couldn't find a way through as the half time whistle blew.
United had fashioned their first chance of the second period with just 34 seconds on the clock when Mellish won a tackle in the centre circle. Zanzala picked it up, and he had just one thing in mind as he approached the edge of the box. He found the gap, but his effort lacked direction.
The Iron responded with some patient work from Gilliead which brought them a corner. Farman caught it, and he sparked a break as he rolled it to Mellish. He combined with Alessandra, before breaking through lines into the final third, and his cut back found Riley up in support. He had two bites at the cherry but strong defending took the sting out of both shots, and Watson gratefully gobbled it up.
A trademark run from Patrick from the halfway line left white shirts in his wake but his cross was put behind. Guy took the corner, and it came to Riley who whipped a ball hard at the gaggle of players. McDonald flicked it but his header took a deflection, and that was just enough to put it beyond the angle of post and bar.
Carlisle should have taken the lead moments later when Riley clipped a superb pass towards the run of Zanzala. Just four-yards out he tried to get the perfect volley, and was hugely disappointed when he somehow crunched it past the waiting target.
The Cumbrians couldn't believe their bad luck once again when Hayden came from deep to meet a Guy set piece. He kept the header down, he got it through bodies, but it bounced off the surface and rose over the bar.
There was then a stunning save from Watson when Guy fizzed a fine free kick at McDonald. His header had power, direction ... but also an alert stopper waiting to claw it away.
But the pressure was made to pay on the hour when Guy once again took the resulting corner. Watson could do nothing on this occasion as Jon Mellish scored goal number 14 for the season with a header that ripped over the line.
It took him just two minutes to turn that into 15 when he stayed forward as another run of chances were blocked and charged down. It eventually came to Guy, and he got his second assist of the night with a stunning outside-of-the-boot pass. Mellish was unmarked and there was no way he was going to miss as he was left all alone to pick his spot.
A cross from Howe after Gilliead had made a move had to be dealt with, but Farman was off his line smartly to make it his.
Another slick Carlisle move saw Patrick and Alessandra bounce the ball off each other before the former went for glory from distance. It was fierce, but he could't keep it down.
Scunthorpe enjoyed a late rally and a cross from Howe was put behind by Guy as Olomola tried to get something on it.
Midfielder Jon Mellish had a hat-trick in mind when he went for it on 89 minutes, having carried the ball forward from the middle third. It was a rapier of an attempt but Watson had it covered.
The Blues saw the game out, maintaining their status as the team with the best home record, and with the highest number of goals scored on their own patch (37) into the bargain.
And the stubborn streak also continued with a third consecutive clean sheet to accompany the third win on the bounce.
Say it quietly, but it's all still to play for.
Carlisle United - Mellish (60, 62)
Scunthorpe United - Loft (45)
Carlisle United - Farman, Tanner, Hayden (c), McDonald, Armer, Riley (Furman 80), Guy, Mellish, Alessandra (Scott 87), Zanzala (Toure 73), Patrick (Walker 87). Subs - Norman (gk), Anderton, Charters.
Scunthorpe United - Watson, Clarke (c), Bedeau, Gilliead, Loft (Olomola 75), Green (Eisa 18), Spence, Beestin (McAtee 75), Karacan, Howe, O'Malley. Subs - Collins (gk), Hippolyte, Rowe, Jessop.
Referee - Samuel Barrott
Assistant Referee 1 - Mark Cunliffe
Assistant Referee 2 - Billy Smallwood
Fourth Official - Ross Joyce
Observer - Jeff Ward
Attendance - BCD