He played with Vertonghen at Ajax before the latter headed to north London for £12m a year before Eriksen.
And Vertonghen insists the Denmark international will only improve after he scored against Newcastle in Spurs' 4-0 Capital One Cup quarter-final victory on Wednesday.
"As a playmaker, I think he can be one of the best in the Premier League," Vertonghen said.
Tottenham v Burnley - Premier League Preview
We had good contact when he was still at Ajax and we always kept in touch
Jan Vertonghen
"I've played with him since he was 16 or 17, so probably for six or seven years now. He's improving every season.
"In the end of his Ajax days, I think they were a bit critical because his stats weren't as good as they should be, they said, but I think he shows now that he can score and get assists as well - and he's a very hard worker.
"He's in first (for training) and he's on the pitch until the last minute and I'm a big fan of his and I'm happy I convinced him to come here.
"We had good contact when he was still at Ajax and we always kept in touch.
"They (Tottenham) obviously asked me what I thought of him and I was very positive, and I think I did my job to convince him to come here."
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