Manchester City boss Manuel Pellegrini is set to turn to big-money signing Nicolas Otamendi to fill the void left by injured captain Vincent Kompany this weekend.
Kompany will miss the Barclays Premier League leaders' home clash with West Ham on Saturday after suffering a calf injury in the midweek Champions League loss to Juventus.
It will be the first time this season Pellegrini has changed a back four that has so far been near faultless, keeping a clean sheet in each of their opening five Premier League games.
Otamendi, a £32million buy from Valencia in the closing days of the summer transfer window, seems the most likely player to step in having come off the bench to replace the influential Kompany against Juve.
Pellegrini said: "It is always serious having injured players, especially the captain and especially in a moment when we didn't concede any goals in the first five games.
"I think it is important to carry on playing with the same names but I always say we have a squad.
"It is important for Nicolas Otamendi to have his opportunity to demonstrate why he is here and Martin Demichelis to return to his performance of last season. We have a squad and we need to replace the captain.
"Otamendi has been working with our team for the last three weeks - maybe not as much as we would like because he went with the national squad, but he is an experienced player, he must have his opportunity in this moment now. I hope he will have a good performance."
City have set formidable standards this season, with five successive wins opening up a four-point lead at the top of the table, and Pellegrini is hopeful they can be maintained in Kompany's absence.
He said: "Tactically we are working in exactly the same way that we did in the other two seasons but we are in a good moment because when individual performances are in a good moment, normally the team is also in a good moment.
"It is not easy not to concede one goal in the Premier League but we hope we can continue."
City are without Samir Nasri, Pablo Zabaleta, Gael Clichy and Fabian Delph but striker Sergio Aguero has recovered from the knee injury that limited him to just seven minutes against Juventus.
"He is 100 per cent and will play without any problems," Pellegrini said.
Record £54million signing Kevin De Bruyne could also make his first City start but Pellegrini, speaking at his pre-match press conference, was non-committal.
West Ham go into the game in good spirits after beating Newcastle on Monday while they have also notched up a couple of notable away wins.
Pellegrini said: "West Ham are doing very well this season, especially playing away. It is not easy to win two games against important rivals like Arsenal and Liverpool without conceding a goal.
"They have nine points in the table - a good total - good players and they are playing very well.
"We know we must be very careful about the counter-attacks and very careful about the set-pieces and try to be a balanced team during the whole game."