Scunthorpe played with 10 men for 80 minutes but held Sheffield United to a goalless draw at Bramall Lane.
Grant McCann received a straight red card for his foul on the Blades' new signing David Cotterill.
Bryan Robson's Blades, who have won only one of their last nine matches, went closest when striker Billy Sharp hit the post against his former club.
The visitors' best chance came from the boot of Paul Hayes, but his shot was well held by Paddy Kenny.
Sheffield United midfielder Gary Speed on fans demanding the dismissal of manager Bryan Robson following the final whistle:
"We've got to stick together in the changing room and work hard on the training ground.
"Of course the crowd does not help but I've seen this before plenty of times in my career.
"You've just got to be brave and demand the ball. If you play for a big club then there are big expectation levels and fans have the right to air their grievances.
"Robbo will take this on the chin and come back even more determined."
Scunthorpe manager Nigel Adkins on playing with 10-men:
"It underlines yet again the character and resilience we've had all season.
"I don't want to comment on the sending-off until I've seen it on video but there are people in both dressing rooms who feel that Grant was unlucky.
"We had to adapt but we looked organised and a cohesive unit.
"This wasn't a game where you could play football because the pitch was not conducive to that so it was all about set-plays and the like.
"My lads crawled off the pitch at the end. They have given their all for each other."
Sheff Utd: Kenny, Geary, Morgan, Ehiogu (Kilgallon 30), Naysmith, Cotterill, Speed, Tonge, Martin (Shelton 82), Beattie (Sharp 60), Hulse.
Subs Not Used: Armstrong, Quinn.
Scunthorpe: Murphy, Byrne (Sparrow 46), Crosby, Hobbs, Williams, Cork, Goodwin, McCann, Morris, Hayes, Forte (May 76).
Subs Not Used: Lillis, Baraclough, Hurst.
Sent Off: McCann (10).
Ref: Rob Styles (Hampshire).