The Warriors moved top of the Magners League last Friday when they beat Ulster 25-13 in Belfast, but their European fortunes are at the other end of the spectrum.
Sean, who will welcome back Scotland joint-captain Chris Cusiter for Friday's Firhill clash, said: "It's a tale of two tables.
"In the Magners League we're at the top but in the Heineken Cup we're at the bottom.
"We need to play like a team that's at the top of the Magners League to do our current position justice."
Glasgow, who lost their two opening Pool 2 games to Newport-Gwent Dragons and Biarritz, have made three changes to the team that won in Northern Ireland.
Chris Cusiter returns to the number nine jersey and Peter Murchie takes over on the wing from youngster Alex Dunbar, while Dan Turner replaces Tim Barker in the pack.
As a result of the changes, Thom Evans moves to the right wing and Richie Gray moves to the left hand side of the scrum.
Sean is now looking for his team to atone for their narrow home defeat by Biarritz, during which Glasgow let slip a nine-point lead.
He said: "We're still disappointed with what happened with the Biarritz game so we need to make sure we're back on form at Firhill to show the supporters what we've got as a professional sports team.
"Last weekend, I was particularly impressed with the way in which the players performed in such a hostile environment, especially our younger forwards like Jon Welsh, Richie Gray and Richie Vernon."
14 Thom Evans
13 Max Evans
12 Graeme Morrison
11 Peter Murchie
10 Dan Parks
9 Chris Cusiter
1 Jon Welsh
2 Dougie Hall
3 Moray Low
4 Richie Gray
5 Dan Turner
6 Kelly Brown
7 John Barclay CAPTAIN
8 Richie Vernon
Substitutes
16 Fergus Thomson
17 Ed Kalman
18 Kevin Tkachuk
19 Tim Barker
20 Calum Forrester
21 Mark McMillan
22 Colin Gregor
23 DTH van der Merwe