The 41-year-old, who has lost his No.1 shirt to Hugo Lloris this season, still has a year to run on his Spurs contract.
Friedel is unsure if his current contract will be his last in football, but he believes he is good enough to prolong his career.
"For me age is just a number," said Friedel. "I would never have signed my last contract if I didn't think I could still perform
"I feel as good as I ever have done.
"Obviously with every athlete in every sport there will come a time when you will have to stop.
"I don't know. We will see if this will be my last contract. Next year could be brick wall time. You never know.
"If I feel the same way now in a year's time, I will revisit the situation.
"But for now I feel the same after matches and heavy workouts as I did when I was 24."