West Ham boss David Moyes says they go to Chelsea to win today.
Victory will see West Ham move ahead of Chelsea into eighth place.
Moyes said: "It's an important game on Sunday, but only as important as the other 35 we've already played. You get the same three points for a win in every match. The time of year makes these games important, and we'll do our best to get a result.
"We're playing Chelsea, who have enjoyed lots of success in recent years, and won many trophies. It says a lot that we're competing with them for a European place, and I think for us to be where we are with three games to go is good, after just coming out of Europe, where we've been for the last three years.
"We're in a tight league position, as we have been all season. We're going to have to do our best in each remaining game to stay there, and hopefully jump up a place or two.
"There are a lot of tough grounds to go to in the Premier League, and Stamford Bridge is definitely one of those. Chelsea have had great teams under the likes of José Mourinho, and they've been really hard to beat, but we'll go there and do everything we can to get the win.
"Chelsea might have wanted to be higher in the league than they are at the moment, but they've been in the FA Cup semi-final recently, and they got to the final of the EFL Cup, so I think it's still been a good year for them and they've shown their quality.
"We beat them when we played them at London Stadium, in what was a really strong start to the season. Unfortunately for us, they've started to hit a bit of form at a time when we didn't want them to hit good form. We have them to play, and we know they've been playing well in recent weeks."
