Carlisle all but sealed League One safety with victory at struggling Oldham - who themselves are only out of the bottom four on goal difference.
The visitors opened the scoring when Oldham lost the ball in midfield and Liam Noble fired home from 20 yards.
They made it 2-0 when Jordan Mustoe superbly lobbed goalkeeper Dean Bouzanis from the edge of the box.
Oldham pulled one back from the penalty spot through Jose Baxter after Mustoe's foul, but Carlisle held on.
The Latics are level on points with Scunthorpe but have two games in hand on the Iron.
VIEWS FROM THE DRESSING ROOM
Oldham manager Lee Johnson told BBC Radio Manchester:
"There's no point masking over it. It was a poor performance.
"People were taking too many touches or not enough touches, and making the wrong decisions. Mentally in the first half, we looked weak.
"At half time, there were a few home truths. At least we restored some pride and a bit of faith with the supporters that they actually feel like we've got a chance of getting out of trouble."
Carlisle manager Greg Abbott told BBC Radio Cumbria:
"We're absolutely delighted to get that win. It was never going to be easy - they're fighting for their lives, they've got some big powerful players and they used that to their advantage in the second half.
"But that's as good as we've played. Some of the football in the first half was absolutely terrific.
"Probably one of the best decisions I've made was to stick with [goalkeeper] Mark Gillespie after his little blip. He was outstanding again when we needed him today. He's 20 years old and great credit to him."