Luger, now 36, scored 24 Premiership tries during two spells at the Stoop before heading out to France to play for Perpignan and Toulon.
And having experienced rugby life on both sides of the Channel, he is backing Quins to be celebrating at the Cardiff City Stadium on Friday night.
"I don't see why Quins can't win it," the World Cup winner told skysports.com.
"It will be a massive game for both sides as their seasons are relying on it, so it should be a fantastic encounter.
"Stade have been struggling this season and from the reports that I've heard they could be cutting back and having a bit of a clearout in the summer so some of them will be playing for their jobs and futures.
"I think there is more for the sides to play for in the tournament this year than in the past. This is their one chance of glory and the pressure will be on."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
$29.99
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.
