A month ago it was against Scarlets. Then Ospreys. Then Munster. Now it is Ulster. Surely they can't all fit into that exclusive category?
Actually, claims Glasgow wing Tommy Seymour, at the time they all did. What marked out all those RaboDirect PRO12 matches was that, in each of them, the team performed and by doing so made the next one the most important game. If at any stage they had lost, they would have had to lower their ambitions and could have slipped into something resembling a comfort zone.
"I don't think it goes stale, though I can see how it might come across that way," he said. "If you are hearing every week that 'this is a cup final' or 'this is the most important game' you are going to start to wonder 'is this the one? Or was it last week? Or is it next week?'
"The next game becomes the most important one when you put yourself in a position to make it so. So we go out and get a big win against Munster; that had been the most important game, and Ulster only became the most important game because of the performance we put in against Munster and the fact that we put ourselves in a strong position to get a play-off place, a strong position to get a home semi-final.
"We need to keep that intensity and mentally prepare ourselves as though we are going into a must-win game in the last game of the season in order to put ourselves in the best position possible four games from now."
The fact is that when Glasgow started this run of games, they were scrapping for fourth place and a qualification for the Pro12 play-offs. Wins over their Welsh rivals should have ensured they get there, but also brought the Irish provinces in second and third places, Ulster and Munster, within range and with that raised hopes of a home tie. If they get there, they raise their sights again and start chasing Leinster, currently in top spot.
Not that Seymour needs much in the way of extra motivation when it comes to facing Ulster, the club where his rugby career began. He has played them often enough to feel that coming up against them is old hat, but can't help having that little buzz when the game comes round.
"It may make me a little bit more edgy, and it may mean a little bit more for me than it does on other occasions, but this is a huge game in terms of us as a club no matter who you are, regardless of what position you play. It can't get bigger than this, so we have to go out and treat it like it was a final," he said.
"They have very dangerous players, there is no doubt about that - you don't need to have trained alongside them to appreciate that - and the skills they have, the finishing ability they have right across the back-line, not to mention some of their forwards.
"They have huge finishing power, a good set of moves and retain the ball well. We have to go out and make sure we put in a huge defensive performance and live up to our name as a good defensive side. We have to make sure we attack as we did against Munster and convert pressure into points and show them a bit of what we have as well."
As the pitches dry out and conditions improve, so does the playing style - the ball was in play for an incredible 54 minutes against Munster - and players like Seymour become crucial, just as was the case last season, when Glasgow finished with a try-scoring flourish.