Last week's defeat to Scarlets has seen the Warriors slip out of the top two PRO12 berths that would guarantee a home semi-final place in the play-offs.
Next up are the Ospreys, who are the defending PRO12 champions and lie five points back behind Glasgow.
Sean told the Evening Times: "It doesn't matter what way you look at the Ospreys game, it is the biggest of the season.
"Basically, we blew it at Scarlets last time out, but the great thing for us is that we have home advantage to try and provide a response to that.
"You look at our last three home games at Scotstoun and we have turned over Ulster, Cardiff and Munster, and all with bonus points in the bag. So we can take huge confidence from that. A huge part of that is the support that we get from all the fans.
"Hopefully with the extra stand going up we will be on course for a new Scotstoun record gate on Friday.
"It is up to us to produce the performance that will deserve."
Sean says last Friday's flop at Parc y Scarlets was his most frustrating game in a Glasgow jersey.
"It was just a bad day at the office when nothing went right. Personally speaking, that is probably the least ball I have seen in a Glasgow jersey," said Sean.
"It was very frustrating but that has just made me even more hungry to get stuck in on Friday.
"You have to give credit to Scarlets, they had a game plan and they, unlike us, executed it to perfection. But that one is gone now.
"We have to channel all our focus on beating Ospreys and getting the play-off bid back on track.
"I think we saw for ourselves at Parc y Scarlets that if our pack gets on top then it just makes such a difference to the quality of ball we get in the backs.
"Ospreys have the best defensive record in the PRO12 so they are just a very solid unit. But at the same time we have no doubt that if we get quick ball we can punish any side in the league.
"However, the Ospreys pack is full of Welsh internationals with the likes of Adam Jones in the front row, Alun-Wyn Jones at lock and Justin Tipuric, who was outstanding in the Six Nations for Wales, at openside.
"So our pack know the challenge that awaits them and they are well up for it."