The former West Ham team-mates were up against each other on Saturday as Chelsea ran out 1-0 winners at the Lane.
Jermain thrust himself into the running for a Euro 2004 spot with a livewire debut for England against Sweden last week.
That came as no surprise to Cole. "I've seen Jermain improve his all-round game gradually but he's always had the knack of scoring goals, which is the most important thing," he said after Saturday's clash.
"He's a top striker, one of the best in the country and he can go as far as he wants in the game.
"In and around the box he's fantastic, great to play with and he's only going to get better. It's a great signing for Spurs and I'm sure he'll score plenty of goals for the club."
So what about Euro 2004? "It's not for me to say," added Cole. "I just know that when he does get his chance he'll score goals, because he's done it at every level so far."
Joe Cole believes Jermain Defoe can go as far as he wants in the game.