Marcelo Bielsa has insisted Leeds captain Liam Cooper "is a huge part of this club" following the arrival of Spain defender Diego Llorente.

Llorente, 27, completed a reported £18million move from Real Sociedad this week, while another international centre-half, Germany's Robin Koch, joined Leeds last month from Freiburg for a fee of around £13m.

Cooper, 29, returned to central defence in last week's 4-3 home win against Fulham after a calf injury and is poised to make his 200th appearance for Leeds in Sunday's Yorkshire derby at Sheffield United.

"In principle I think he will play and Cooper is a huge part of this club," Bielsa said. "I'm referring to the patrimony between him and the institution.

"Institutions are bigger when they have patrimonies like this, when they have someone who behaves in an impeccable manner, as Cooper does."

Leeds' versatile defender Gaetano Berardi sustained a long-term knee injury at the end of last season and Ben White returned to parent club Brighton, where he has since signed a four-year deal.

That left Bielsa desperately short of specialist centre-halves and in Cooper's absence, Pascal Struijk partnered Koch at the heart of defence in Leeds' opening-day Premier League defeat at Liverpool.

"It's not that we plan to play with a back three more often and it's not to increase competition, because Pascal played a very important game against Liverpool," Bielsa said of Llorente's arrival.

"Koch is the only right-sided centre-back we have at the moment and if he got injured we would have had to get someone very young from the youth team or we would have had to move (Luke) Ayling or (Kalvin) Phillips out of position.

"We don't have Berardi and with Ben White having left, it was necessary to have two players to count on in this position."

Sunday's clash at Bramall Lane will be the first time the two sides have met in the Premier League since 1994.

Leeds have taken four points from their first two games back in the top flight, while the Blades are bidding to kick-start their season after successive defeats to Wolves and Aston Villa.

But Bielsa expressed his admiration for Blades boss Chris Wilder and his side following their top-10 Premier League finish last season.

"They are a very good team and have consolidated and it's a good opportunity to compare ourselves to them," Bielsa said.

The 65-year-old, who has managed in Mexico, Spain, Italy and France, said he had yet to witness a more fierce rivalry than the one between former club Newell's Old Boys and Rosario in his native Argentina.

"In all the derbies I've watched or coached in or analysed, I've never seen an intensity or an importance that is (comparable to) the game between Newell's and Rosario," he added.