Les, one of the great modern-day strikers, returns to the Lane with fellow ex-Spurs Ian Walker, Steffen Freund and Ben Thatcher for Sunday's televised clash.
Injuries hit hard in his five-and-a-half years at the Lane but he still bagged 33 goals in 97 league starts between his arrival in August 1997 and departure to West Ham in January 2003.
Now 37, he switched to Leicester in the summer and is in fine form with 10 goals so far this season.
"We have to look out for Les," warned Gus. "He's on fire, scoring goals and we have to be ready for him.
"If you asked for one word to describe him I would say 'gentleman' - on the pitch, off the pitch, going out with him, he's a great guy.
"There are not too many people in football like that and you have to be proud to have played with him and enjoyed life with him because he is a magnificent guy."
So dangerous in the air himself, Gus admits Les is at another level.
"It is very difficult to mark him," he added. "You think you are in the right position and you are strong enough to stop him but he will get in front of you, stronger than you, climb all over you and head that ball.
"He's so powerful, great movement. He is the best I've played with in the air.
"You can also rely on him. When you are playing with Les you can always look forward and even if it's not a perfect pass, he will get that ball and hold it for you. That is something you appreciate."
Gus Poyet has one word for Les Ferdinand - 'gentleman'.