Colin made his Glasgow debut as a second-half replacement for Dan Parks against Neath/Swansea Ospreys last week, scoring Glasgow's only try in an 11-33 defeat.
He starts the Cardiff game as Dan Parks in on international duty with Scotland and Calvin Howarth is recovering from a shoulder injury.
Rory Kerr and Graeme Beveridge return after injury, respectively at right wing and scrum half, and Paul Dearlove resumes in the starting XV at blind side.
Jon Petrie leads the side in the absence of his back-row colleague, Cammy Mather.
Glasgow
15 Glenn Metcalfe
14 Rory Kerr
13 Graeme Morrison
12 Alan Bulloch
11 Sean Lamont
10 Colin Gregor
9 Graeme Beveridge
1 Euan Murray
2 Scott Lawson
3 Lee Harrison
4 Andy Hall
5 Nathan Ross
6 Paul Dearlove
8 Jon Petrie (captain)
7 Donnie Macfadyen
Substitutes:
16 Simon Gunn
17 Andy Kelly
18 Joe Beardshaw
19 Roland Reid
20 Sam Pinder
21 David Millard
22 Moffat">Stuart Moffat