Spurs travel to the London Stadium after securing a 2-0 win over north London rivals Arsenal on Sunday to maintain the pressure on Premier League leaders Chelsea.
Tottenham, who remain four points behind the Blues, will now be looking for a win over the Hammers which would cut the gap at the top of the table to just one ahead of Chelsea's home match with Middlesbrough on Monday night.
And Spurs manager Pochettino believes his side's London derby clash against 15th-placed West Ham could be key in which team ends up lifting the trophy in May because of the pressure it would heap on Chelsea should Tottenham triumph in east London.
"We have reduced the gap to Chelsea again. And now we have to be focused because we have on Friday a very important game against West Ham," Pochettino said after Tottenham's 2-0 win over Arsenal.
"We will have the chance to play before. It will be a tough game and a difficult game and if we are able to win we will see what happens.
"It could be (important). The race for the title is down to four points and we will see what will happen."