Johnnie Jackson's strike saw Charlton beat second-placed Sheffield United and move seven points clear at the top of League One.
Jackson fired the Addicks ahead midway through the first half with a direct free-kick, after Danny Hollands was brought down by Neil Collins.
Charlton were reduced to 10 men late on after Darel Russell was dismissed for a foul on Kevin McDonald.
Blades striker James Beattie was also shown a red card for violent conduct.
His dismissal came after he was involved in the melee following Russell's sending-off.
United had earlier a goal ruled out when Richard Cresswell was adjudged to have fouled goalkeeper Ben Hamer.
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Charlton manager Chris Powell told BBC London 94.9:
"We were playing good opposition - good players under a good manager - but my team really dug in today and were really professional.
"In the end it was won by a set piece and it was an outstanding free-kick by Johnnie Jackson.
"Today was a tight affair. Both keepers made good saves, some heroic defending at both ends so it is always going to take a moment of quality to really win you the game and that happened for us today."
Sheffield United manager Danny Wilson told BBC Radio Sheffield:
"I thought for large parts of that game we were very much the aggressors. I think they have been very fortunate.
"We've not really had the bounce of the ball at times, particularly in the box. I just felt, particularly in the second half, we were outstanding.
"Some of our football was exquisite at times and I feel for the lads and the fans because there was a result there for us."