John has played as a replacement in the past two league matches – the win against Edinburgh two weeks ago and the game against Dragons. Glasgow coach Hugh Campbell thinks 18 year old John is up to the challenge: "Johnny is young, raw and has a lot of learning still to do but he is ready for this step up.
"It is a big ask for a lad of his age,but I believe he will cope well and do a good, solid job for us."
John replaces Jon Petrie, who has to miss the trip to Swansea because of illness. The Glasgow captain has not shaken off the bug that made him doubtful for the match against Dragons last week, though he played in that game. Gordon Bulloch will skipper Glasgow.
Cammy Mather also comes into the backrow, playing his first game after a five month lay-off. Cammy comes in for Paul Dearlove who fractured his right fibula during the league match against Newport Gwent Dragons last Friday.
Steve Swindall of Glasgow Hawks has been called into the replacements.
Glasgow make another two changes to the starting line-up. Andy Craig and Kenny Logan step in for fellow caps, Graeme Morrison and Rory Kerr. Rory is on the bench while Graeme is rested.
Glasgow
15 Scott Barrow
14 Sean Lamont
13 Andy Craig
12 Andrew Henderson
11 Kenny Logan
10 Dan Parks
9 Sam Pinder
1 Kevin Tkachuk
2 Gordon Bulloch (captain)
3 Lee Harrison
4 Andy Hall
5 Dan Turner
6 Cammy Mather
8 John Beattie
7 Donnie Macfadyen
Replacements
16 Scott Lawson
17 Andrew Kelly
18 Andrew Wilson
19 Steve Swindall
20 Graeme Beveridge
21 Calvin Howarth
22 Rory Kerr