The Argentinian endured a difficult start to life in the Premier League.
The 24-year-old endured a poor start to his time in the Premier League, but he has started to show this season exactly why the club signed him in the first place.
And after playing alongside the attacking midfielder from when he first arrived from Roma in 2013 until Defoe left for Toronto the following year, the Sunderland striker insisted that he was pleased to see his former teammate doing so well.
"It's nice to see someone like Erik Lamela doing so well because I was there with Erik and there were times when there was a lot of pressure on him," he told Sky Sports.
"He'd come to the club for a big fee and you could see at times it was really getting to him because he wanted to do well but the Premier League's a difficult league.
"But now seeing him do well is unbelievable."
Lamela has scored four goals and contributed seven assists in the league to help Mauricio Pochettino's men move into the title picture in the top flight.
It is perhaps his consistency that has been such a revelation in recent times. While Spurs fans were often treated to moments of brilliance - such as the rabona goal in a Europa League game in 2014 - they were arguably too few and far between for him to be relied upon to be a key player for the club.
However, this season he has been influential on a much more regular basis, so will surely be one of the men that Pochettino looks to to help the side overturn the five-point deficit to Leicester at the top of the table.