The Saints have impressed under Pochettino since he arrived at the club in January, beating the likes of Manchester City, Liverpool and Chelsea, but the Argentinean boss expects a different kind of match against Sam Allardyce's men.
The 41-year-old told reporters: "I think West Ham are going to be very direct, very aggressive and play the long ball to try and keep us in our half.
"There were many times during the game against Liverpool when this was effective for them - we have to take into account that their players are very tall and aggressive, very physical.
"We have to try and impose our brand of football, be dynamic and keep going forward. We also need to be aware that we will suffer against them when we don't have the ball."