Defoe acknowledges that he cannot afford to rely on his reputation as a goal-getter to get him international recognition.
He told Sky Sports News: "In a World Cup year you have got to play, it's as simple as that.
"To get into any England squad, it's based on merit. So you have got to play, I understand that. I also understand that it's a long season, there are so many games to go and a lot of football to be played. I just have to try and keep myself sharp and fit.
"It has been really frustrating. When you have played in a World Cup and have been involved with the England squad for a number of years, it's just the best thing in the world - representing your country at that level. You want to play."
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