The Ireland lock is also likely to miss the final Pool 4 game away to Castres in two weeks' time due to a troublesome calf injury, which flared up again during last week's Pro12 win over the Scarlets.
Coach Mark Anscombe is expected to bring in Ireland blindside Iain Henderson to partner Lewis Stevenson in the second-row, while Robbie Diack looks set to continue his impressive form of late in the No 6 jersey alongside skipper Chris Henry and Nick Williams in the back-row.
Ulster have nominated Dungannon winger Chris Cochrane as an additional player, with his injured club colleague Chris Farrell deregistered.
Cochrane (24), who is on a development contract and who learned his trade at the same Coleraine alma mater as Andrew Trimble, has made six appearances for Ulster and, in the current injury crisis at Ravenhill, is likely to find himself on the bench for tomorrow night's clash.
With full-back Adam D'Arcy fracturing his ankle last Friday, Kiwi Jared Payne is now almost certain to start.
Meanwhile, Rory Best, Europe's best turnover merchant, according to the statistics this season, says that everything that Ulster have achieved so far this season will mean nothing if they don't win tomorrow night.
"We have talked a lot about how it was brilliant to be unbeaten in the earlier months of the season. But really the time to be unbeaten is in January or April and May, that's when you want to be undefeated," said Best, raring to go after a couple of weeks' rest.
"Let's not forget that Glasgow are just behind us in the Pro12 and they are definitely at their most dangerous when people start to write them off.
"The fact that they are out of Europe means nothing. They will come to Belfast with a good run of wins behind them and they want to keep up the momentum and finish in Europe with two big performances.
"Obviously, to get where we want to go, we have to beat the best anywhere. To get a home tie for the quarter-finals is something that Ulster have never done before in the current format, so it would be a big achievement for us. It will be important to us.
"First and foremost, we must win on Friday night, and then we can re-assess things on Monday, with regards to the following week when we travel to Castres. I believe the team has enough firepower to win the two games.
"We have to make sure we start well, that's essential. That will put more pressure on them on the pitch and attempt to squeeze the life out of them. To do that we must make sure that we are physical at the breakdown in particular. We have put ourselves in a great position in the group, now is the time to finish the job off."