Second-placed Glasgow can still secure a home play-off, but Ulster are also playing for home advantage next weekend.
With an increased capacity of around 10,000 it will be the club's biggest home crowd for a regular season game and tickets for this match sold out in record time.
Following last week's defeat to the Ospreys, Sean Lamont returns from injury and replaces Niko Matawalu on the left wing, with the Fijian international moving to scrum-half in place of Henry Pyrgos.
The only other change to the backline sees Finn Russell come in for Duncan Weir at stand-off.
In the pack, Dougie Hall replaces Pat MacArthur at hooker and Rossouw de Klerk returns from injury to take the place of Jon Welsh at tight-head.
Kellock comes into the second-row to make his 156th appearance for the club.
Josh Strauss moves to blindside flanker replacing Rob Harley, with Adam Ashe returning from injury at Number 8.
Mike Cusack also makes a return from injury for this game and the prop has been named among the replacements.
Glasgow Warriors head coach Gregor Townsend said: "Ulster are a really strong side who have been playing excellent rugby and we know we'll face an extremely tough challenge at Scotstoun tomorrow afternoon.
"We've had some titanic battles with Ulster over the last few seasons and they play with a lot of passion and competitiveness and they will fight hard for everything.
"With all the games being played simultaneously it will be an exciting afternoon of rugby and we're very motivated to improve on last week's performance against the Ospreys.
"Playing in front of around 10,000 supporters at home for only the second time in our history is sure to be a great experience for our players. We will be doing all we can to reward our supporters with a home semi-final the following week."
Glasgow Warriors team to play Ulster, GUINNESS PRO12, Scotstoun Stadium, Saturday 16 May (kick-off 3pm) - live on Sky Sports 1:
15. Stuart Hogg
14. Tommy Seymour
13. Richie Vernon
12. Peter Horne
11. Sean Lamont
10. Finn Russell
9. Niko Matawalu
1. Ryan Grant
2. Dougie Hall
3. Rossouw de Klerk
4. Jonny Gray
5. Al Kellock (Captain)
6. Josh Strauss
7. Chris Fusaro
8. Adam Ashe
Replacements
16. Pat MacArthur
17. Gordon Reid
18. Mike Cusack
19. Leone Nakarawa
20. Ryan Wilson
21. Henry Pyrgos
22. Duncan Weir
23. Peter Murchie
Not available due to injury: Alex Allan (shoulder), Mark Bennett (shoulder), Fraser Brown (hamstring), Alex Dunbar (knee), Tyrone Holmes (knee), Sean Maitland (shoulder), Tim Swinson (ankle) and DTH van der Merwe (hand).
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