The pair used to lead the line together for Ireland Under-17s and have progressed all the way through to the senior set-up together.
Robbie, of course, has made a huge impact at international level with 13 goals in 37 caps at the tender age of 22.
He was the star of Ireland's World Cup campaign with three goals in four games and Gary, who didn't quite recover in time from a broken leg to make the squad for Japan, was delighted to see him walk through the doors at the Lane.
'Doc' beamed: "I think we've signed one of the best forwards in the Premiership, I've said that all along.
"I remember in my first season I had to play against him here and he absolutely ripped me to shreds.
"I've seen him close-up for Ireland and what's he's done there. I thought he was our best player in the World Cup, even ahead of Damien Duff. It's a hell of a signing to be honest.
"I don't really know what happened at Leeds but it looks like they just prefer Kewell, Smith and Viduka.
"But I know from the experience of playing with and against him what a great player Robbie is and he's still young, so it's a great investment for the club."
Gary Doherty knows better than most the impact Robbie Keane can have at Spurs.