Promotion-chasing Sheffield United were held to their third consecutive goalless draw at Bramall Lane by a determined 10-man Carlisle.
The visitors came closest to breaking the deadlock just before half-time when Liam Noble's drive hit the post.
Blades loanee Jonathan Forte should have scored midway through the second half but scuffed his shot wide.
Sean O'Hanlon was dismissed for a second yellow card as the hosts pushed for a winner but Carlisle held on.
VIEW FROM THE DRESSING ROOM
Sheffield United manager Danny Wilson told BBC Radio Sheffield:
"The players in the system that Carlisle applied today is very difficult to breakdown.
"I make no excuses for not breaking them down, you need a shade of luck at times and we didn't have it.
"We've had a couple of great opportunities in front of goal and not taken them and it happens.
"The positive from where I'm sat is that we've moved up a place."
Carlisle United manager Gregg Abbott told BBC Radio Cumbria:
"I'm disappointed we didn't get three points. On performance and chances and general play I thought we were excellent.
"It was only the last 15 minutes where a referee decides to get involved with a game that he doesn't need to get involved in and stops our momentum.
"If O'Hanlon is going to get sent off for that, there could've been eight sendings off in the game when there shouldn't have even been a yellow card. It was a terrific game with spirit and determination - not one bad tackle in the whole of the game and he decides to get involved and make a decision that we're talking about.
I don't even want to talk about him because it's that bad that I don't think you'll ever have an eleven versus eleven if that's what you're getting sent off for. Technically he's probably correct, but practically he wants shooting."