The defeat leaves the Aviva Premiership side 10 points adrift of Pool Five leaders Stade Francais with just two games remaining.
The French visitors put themselves firmly in control through a brace of first-half tries from hooker Laurent Bouchet, with scrum-half Valentin Courrent adding a conversion and a penalty to make it 15-6 at the break. Alex Davies scored two penalties for Welsh.
The second half started in much the same vein as Florian Ninard scored a converted try in the 42nd minute to stretch the lead out to 16 points.
Mike Denbee gave the home side hope heading into the final 10 minutes as he grabbed a try which Davies converted, but straight after Lotu Taukeiaho killed off any hopes of a comeback with a bonus-point try for Grenoble.
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.
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.