Bates said: "With some illness in the squad, the final bench cannot be confirmed at this time."
On the narrow defeat to Edinburgh Gunners on Boxing Day, Bates was quick to support the efforts of his side: "We were very competitive in a lot of areas. They created very little but unfortunately we handed them a lot," he said.
The team remains unchanged from the Boxing Day clash apart from Andy Miller who replaces the injured Scott Gray in the back-row.
Stand-off Gregor Townsend and winger Simon Danielli await a fitness test on Friday to confirm their participation.
14 Simon Danielli
13 Ben MacDougall
12 Charlie Hore
11 Nikki Walker
10 Gregor Townsend
9 Chris Cusiter *
1 Paul Thomson (CAPTAIN)
2 Ross Ford *
3 Bruce Douglas
4 Scott MacLeod
5 Opeta Palepoi
6 Kelly Brown *
8 Semo Sititi
7 Andy Miller
Substitutes from: Tom McGee, Steve Scott, Colin Stewart, Brendan McKerchar, Andy Rennick, Calum MacRae *, Matt Parr, Mark Blair, John Dalziel, Garry Law
* = Indicates member of Scottish Institute of Sport