But Pellegrini is anticipating a backlash and warned: "I expect to see a team that will try to reverse their results.

"They have a lot of top players so we cannot be confident that, just because they are not in a good moment, we are going to win the game. We must try to win the game by having a good performance.

"The advantage we will take is if we play a good game, if we are solid in defence and creative in attack. That's what the result depends on.

"It's strange for a big team (that in) the last 20 years normally play in the Champions League, but football is like that. From one game to another the results change.

"Is it a good time to play them? The time for our team depends more on our performance than what is happening with the other team."

Freddie Ljungberg will be in the opposition dugout as Arsenal's search for a permanent new manager goes on.

Pellegrini admits the Swede, a former Gunners and Hammers midfielder, has a tough task on his hands.

"Of course for him it is a big challenge in a bad moment for Arsenal," added Pellegrini.

"He is a young manager just starting his career and he will do it the best he can do it. It is not easy but he knows that club well."

Pellegrini has problems of his own, with West Ham edging perilously close to the drop zone, but as usual he rejected any suggestions that he is battling to save his job.

"As I always say, the pressure doesn't link with the results," he said. "The pressure for me is in every game, to do it better, play well and win the game.

"You do not need to be in a bad position, without a win in so many games, to start to feel the pressure. Pressure is there always."