Marcelo Bielsa was left frustrated after Leeds United were unable to make their dominance pay in a 1-0 defeat at home to promotion rivals Sheffield United.

Second welcomed third to a bouncing Elland Road for an all-Yorkshire clash that could go a long way to deciding promotion to the Premier League.

Leeds were the better side on Saturday lunchtime but failed to capitalise on their chances, allowing Chris Basham to fire the Blades to a 1-0 win that saw them usurp the hosts in the table.

Kiko Casilla was sent off late to rub salt into the hosts' wounds, with Leeds head coach Bielsa expressing his disappointment in a post-match press conference played out to the backdrop of a fire alarm.

"I don't want to underestimate the victory of the opponent," the Leeds boss said.

"If we analyse the game, we can't be unsatisfied but we're disappointed with the result.

"If the opinion is that we deserved to draw, I have a different opinion on it.

"What happened today has happened many times in the past games.

"To explain it again after such an important loss at home with our fans, our first half hour was very good.

"We conceded the last 10 minutes of the first half but we had less quality in the second half but we dominated and we had the feeling that we were dangerous."

The driving rain and sodden pitch continued to make for difficult conditions after the break, yet both sides fought on manfully and Tyler Roberts smacked the outside of the post as Bielsa's men pushed.

But Sheffield United dug deep and capitalised on a 71st minute error by Leeds captain Liam Cooper as Billy Sharp put in Basham to score from the edge of the box.

Pontus Jansson, by now limping heavily, went closest to levelling after being deployed as makeshift frontman, but ended the match in goal after Casilla was sent off for bringing down Sharp at the death.

"Great victory, not a great performance," Sheffield United boss Chris Wilder said afterwards.

"I've said all along I am not going to be embarrassed about winning against the run of play a little bit.

"Because I think in 18 months at this football club, we've smashed some sides and not got what we've deserved.

"Half a dozen times last year, I've sat in my office thinking 'how have we not won it?' having drawn let alone lost it.

"It was a tough afternoon, a tough test for us and delighted against the run of play that we've come away with a result."

The celebrations at full-time belied Wilder's post-match comments downplaying the importance of this match in the automatic promotion race.

The Sheffield United manager repeated after that this was not a "season-defining" win but he was proud of the character epitomised by match-winner Basham.

"He's done well to be the match-winner because he was coming off after 25 minutes because he was absolutely useless," Wilder said.

"I was going to do what their manager does and drag him off, but we kept him in it and I think he epitomised what a Sheffield United player is.

"He dug himself out of a hole and other players dug him out of a hole because he didn't have the greatest of halves of football.

"To come up with the winner was great for him. They're a good side, a really good side."