DTH van der Merwe returns to the Glasgow Warriors starting XV. The Canada international winger, who was ruled out for the remainder of the season following shoulder surgery in February, has recovered four weeks ahead of schedule.
The 33-year-old scored the dramatic winning try in Glasgow's last league semi-final victory in 2015, also against Ulster at Scotstoun.
Sam Johnson and Kyle Steyn start in midfield for the fourth consecutive game while recent recipient of the Guinness PRO14 Young Player of the Season award, Adam Hastings starts at fly-half and Ali Price is once again named at scrum-half.
Dave Rennie said: "We're in a much better place than we were 12 months ago and have trained with a real edge during this three-week break.
"DTH is back earlier than we expected which is a big boost. His power as well as his experience of knock-out rugby will be invaluable tomorrow night.
"We know Ulster will be a completely different animal to the side we faced here last month and we're going to have to play better than we did that day to get the result.
"We're all determined to a be a part of a Glasgow Final and know we're going to have to play our best rugby of the season to get there."
15 Stuart Hogg
Unavailable players: Bruce Flockhart (shoulder), Chris Fusaro (hamstring), Siua Halanukonuka (shoulder), Nikola Matawalu (knee), Robbie Nairn (thigh), Matt Smith (shoulder), Tim Swinson (ankle) and George Turner (head)