Southampton boss Mark Hughes has said that his side must capitalise on the "negative" atmosphere around the club if they are to earn victory on Saturday.
Hughes, whose side are two points adrift of safety in the table, could leapfrog their opponents with three points at the London Stadium.
"It's a key game for both sides," the Saints boss told reporters. "With the situation we find ourselves in, and West Ham as well, at this time of the season if you've got the opportunity to affect teams close to you in the league you can damage their prospects and enhance your own.
"That's our intention, to go there with a positive mindset. West Ham have their own problems to deal with, it seems, with their home games so we have got to take the opportunity, if it presents itself, to be able to exert pressure on them and maybe affect the atmosphere in the ground and what seemed to occur against Burnley.
"That had a detrimental effect on the team and it's within our ability to do that ourselves. We have got to try to be positive and get on the scoresheet first. We've got to affect the confidence of their group. Clearly there is some anxiety surrounding the club at the moment. That's a negative and it certainly affected them in the last game, going by what some of their players talked about afterwards."
The Saints are looking for their first win in the league since February.
