Pellegrini believes Chelsea, who are top of the table after winning all five of their games this season, will present a different challenge.
'We will see if he is fit for Sunday.
The Blues are now the best team in England - winning each and every game under their new boss Maurizio Sarri and Pellegrini will know that it will not be a walk in the park trying to stop Eden Hazard and co. Against Brazil in the quarter-finals, Hazard was sensational, the most skilful player on the pitch.
He now has 15 successful penalty kicks in the English top flight, and while he had missed two, these were rendered academic as they did not have any effect on the results of those matches - a 1-0 win over Crystal Palace in May 2015 and a 2-1 triumph over Manchester City in April 2017. We have to go step by step and just try to win the next game. We have to concentrate defensively, but I am confident.
And Jack Wilshere, who joined the Hammers from Arsenal in the summer, is sidelined with an ankle problem.
But I don't think he quite realises how good he can be and what exactly you need to do to get every last ounce out of yourself to be the best.
'He was working so well that of course he was very upset about what happened.
"I spoke with him before he started the week".
"David Luiz is in Cobham because he [did not play for] six months so I thought it was better for him to have rest", Sarri said. As did Pedro Obiang.
Chelsea have made a flawless start to the season, winning all five of their games, but Pellegrini urged his players not to be intimidated by the form of the league leaders.