Match ends, Sheffield United 0, Brentford 0.
Promotion-chasing Brentford had to settle for a draw in a game which saw referee Eddie Ilderton change his mind about sending off Sheffield United's Kieron Freeman and awarding a penalty.
Freeman was dismissed after he was ruled to have fouled Marcello Trotta.
But, after consulting with assistant Mark Dwyer, Ilderton rescinded the red card and gave a drop ball.
"He got it wrong but he put it right," said Blades boss Nigel Clough. "It takes a lot of courage to do that."
The Bees stay second in League One, five points clear of Leyton Orient.
But there was only one talking point after the game, and Clough praised Ilderton for getting the decision right - eventually.
"He has to be commended for putting it right," the Blades boss said.
"We wish he hadn't got it that wrong in the first place, but he waited in the tunnel and talked to the lads at half-time and said he had a bad angle, so that is absolutely fine, everyone got on with the game. But it was very, very brave and the correct thing to do.
"If he'd have just given himself 30 seconds ... but as long as you get the right decision in the end, that's the main thing."
Brentford manager Mark Warburton called the decision 'bizarre.'
"I have never seen anything like that in my life before," he said.
"The obvious thing to do is just take your time and go over and speak to your linesman and then make your decision.
"But he has brandished the red card and given the penalty and all of a sudden we end up with a drop ball. It was absolutely bizarre, I have never seen anything like it before.
"I haven't seen it again, but the fact of the matter is he has brandished the red card and pointed to the penalty spot."
Brentford had their best chances in the opening 20 minutes as Trotta had a shot blocked while Clayton Donaldson and Toumani Diagouraga put efforts wide.
United's best opportunity came through Billy Paynter, who was brilliantly denied by a last-ditch tackle from James Tarkowski as he was about to put Conor Coady's cross into an unguarded net.
- 22DaviesBooked at 90mins
- 7FlynnSubstituted forKennedyat 90+2'minutes
- 18PaynterSubstituted forPorterat 59'minutes
- 14McGinnSubstituted forBaxterat 84'minutes
- 12McCormackBooked at 40mins
- 5CraigBooked at 90mins
- 9DonaldsonBooked at 81mins
- 18JudgeSubstituted forDallasat 79'minutes
- 20DiagouragaBooked at 59minsSubstituted forSavilleat 71'minutes
- Eddie Ilderton
- Shots on Target
Second Half ends, Sheffield United 0, Brentford 0.
Foul by Chris Porter (Sheffield United).
Tony Craig (Brentford) wins a free kick in the attacking half.
Substitution, Sheffield United. Terry Kennedy replaces Ryan Flynn.
Tony Craig (Brentford) is shown the yellow card.
Conor Coady (Sheffield United) wins a free kick in the attacking half.
Foul by George Saville (Brentford).
Ben Davies (Sheffield United) is shown the yellow card.
Foul by Ben Davies (Sheffield United).
Clayton Donaldson (Brentford) wins a free kick on the right wing.
Attempt saved. Marcello Trotta (Brentford) left footed shot from the centre of the box is saved in the centre of the goal.
Attempt missed. Stuart Dallas (Brentford) right footed shot from the right side of the box misses to the left.
Corner, Brentford. Conceded by Kieran Freeman.
Corner, Sheffield United. Conceded by Alan McCormack.
Attempt blocked. Ryan Flynn (Sheffield United) right footed shot from the left side of the box is blocked.
Attempt missed. Marcello Trotta (Brentford) header from the centre of the box misses to the left.
Corner, Sheffield United. Conceded by Tony Craig.
Substitution, Sheffield United. Jose Baxter replaces Stephen McGinn.
Clayton Donaldson (Brentford) is shown the yellow card.