Defoe came off the bench at Newcastle United to score in their 2-2 draw.
"With the sharpness I've got now, I believe I should be playing," said Defoe. "When you're playing well, I believe you should play. I feel completely different from how I did last season.
"I probably came back too soon after injuring my ankle with England last September and sometimes it's difficult after an injury to get that sharpness I'd always had. But I now feel as strong as I've felt for a while, probably the strongest I've felt in my whole career.
"My England record is good [15 goals in 46 games] and I was disappointed not to be in the last squad but it makes you more hungry. When I'm fit and sharp, and in the form I'm in now, I can score goals at that level. I've done it before.
"The manager knows what I can do, especially with playing in the last World Cup and gaining that experience. I look forward to seeing what happens but I will do whatever it takes to get on the plane, like I did last time. I always say that if you put in the hard work, it pays off. I was looking forward to the game against Newcastle and I was disappointed not to start but when you put the work in, it's easy on match day."