The 31-year-old has began just one Premier League match this season following Roberto Soldado’s arrival at White Hart Lane in the summer.
Defoe, who has been connected with a January switch to his former club West Ham, was a member of England’s 2010 World Cup squad but admits he may be overlooked by Roy Hodgson for next summer’s tournament in Brazil.
“Getting into a World Cup squad is based on merit and you have to play for your club,” said Defoe.
“As a forward, if you are not getting the chances, it will be difficult.
“Frank Lampard got it right when he said the other day that everyone is fighting [for places].
“It’s important that everyone goes back to their clubs and plays games to try to impress the manager.
“It’s a long way to go before the World Cup. There is a lot of football to be played and we will see what happens. You never know, I might play every game from now on.”