Warriors completed their regulation season with a 37-32 bonus-point victory at Scarlets last Friday leaving them third in the standings - their best ever finish.
The other play-off match will be an all-Irish affair with Leinster hosting Munster.
Sean told the Evening Times: “It is going to be a huge ask to get the win over Ospreys and make the final of the play-offs.
“Every player in a Glasgow jersey will need to play the game of their lives if we are to do it.
“The Ospreys have so much talent in depth and you saw, from the way they almost beat Biarritz in the quarter-finals of the Heineken Cup away from home, just how good they are.
“They have come through very strongly and at their place they are a match for anyone.
“That said, we have a good record on the road this season and Friday’s win at Scarlets was our fourth away victory. On top of that, we are going into this game with four wins on the bounce behind us so we have real momentum.
“So while we would love to have had home advantage and a Firhill semi-final, we will take what we’ve got and give it everything.”
John Barclay will return for the semi after he was rested due to a shoulder injury. Max Evans, who was forced to withdraw from Friday night’s game, should also make it and Chris Cusiter is expected to shake off the knock that saw him subbed after the interval at the Parc Y Scarlets.