Luke Marshall will be out for up to six weeks after fracturing his finger during Ulster's recent PRO 12 victory over Scarlets.
He is joined on the sidelines by Adam D'Arcy who fractured his ankle.
D'Arcy will see a specialist later in the week when an approximate time frame for a return to action will be confirmed.
There is some good news though as Dan Tuohy, whose calf injury recurred against the Scarlets, has been named in the squad and will be monitored throughout the week.
Jared Payne, who missed the clash with the Welsh side because of a groin strain, is also included.
But their fitness will be tested throughout the week before a decision to play them is made.
"They're both muscular injuries so we'll lighten the workload for them this week and see how they respond to that and we'll make a call later in the week if they're going to be up and ready for Friday night," coach Mark Anscombe explained.
"You know we're comfortable with the players that come in and replace those injured and to survive you've got to have depth and we're comfortable with our depth at the moment and it gives them an opportunity and we've just got to go about our work and believe in what we've got to do."
Hooker Rory Best said that Glasgow could prove a dangerous side to play on Friday.
"They have nothing to play for so that leaves them that they can go and play a bit of rugby and when this Glasgow team plays rugby they're a lethal team," he said.
"We need to make sure that we put a lot of pressure on them and keep the squeeze on them and ultimately bring a bit of physicality and a bit of edge and when we've brought that this season we've won the game."
Glasgow are yet to register a win despite coming close on all four occasions, especially in their nail-biting back-to-back games against Castres.
Ulster will know, however, that if they can secure a win at Ravenhill, they will be in poll position to top their group.
Forwards (16): Callum Black, Tom Court, Declan Fitzpatrick, Adam Macklin, John Afoa, Rob Herring, Rory Best, Lewis Stevenson, Dan Tuohy, Iain Henderson, Neil McComb, Mike McComish, Chris Henry, Robbie Diack, Roger Wilson, Nick Williams.
Backs (11): Ruan Pienaar, Paul Marshall, Michael Heaney, Paddy Jackson, Paddy Wallace, Darren Cave, Michael Allen, Craig Gilroy, Andrew Trimble, Chris Cochrane, Jared Payne.