The Hammers travel to White Hart Lane two points ahead of their London rivals.
Spurs have lost their last three Premier League games - that included a home defeat to lowly Wigan - while winning just two of the last nine in all competitions.
But the 20-year-old defender insists: "It's important for us to get our form back in the league.
"We made a good start to it. We hit a bit of a dip in form but we're a good bunch of lads and we're working hard every day to put it right.
"There's no denying it's a massive game for us and we're confident we can get three points and put the season back on an upwards spiral."
And Caulker is desperate to help the North Londoners qualify for Europe's top club competition next season: "I'd love to play in the San Siro but that's a bit out of sight at the moment - hopefully next season if we can finish top four.
"If you ask all the lads and manager we're all motivated to get in the Champions League, so our motivation is to get in the top four this season."