The 31-year-old has scored two goals in three senior international appearances this year and has vowed to do all that he can to book a place on the plane to Brazil.
"I know how hard it will be," he told The Mirror. "It is something I will be fighting for and I know I have to do well for Southampton.
"I know I need to score goals, but even that might not be enough to get me the nod. It might be a shoot-out between me and Andy Carroll.
"I'm not going to lie - I think that is one of the major possibilities. I will focus on my game and, when Andy is back from injury, he will be raring to go as well. So it's up to Roy Hodgson to make his decision."
Carroll has not featured at all this season due to a long-term foot injury, but club medics are hopeful that he could return when the Hammers host Fulham on November 30.