The Dons, who lost 7-3 on aggregate to Bayern Munich in the UEFA Cup in 2007-08, take on Qarabag in Baku in the first leg of their play-off, with a place in the inaugural ECL's group stage up for grabs.
Glass said: "It's the most important game of the season so far, it's the most important European game for close to 15 years, so it's not lost on the group how important it is.
"We're ready for it, we've had a great pre-season, we've had a reasonable start to the season as well."
The Dons beat Swedish side Hacken in July and Breidablik, of Iceland, earlier this month to secure their trip to Azerbaijan.
Glass's side have also won their first two Cinch Premiership matches, against Dundee United and Livingston, before Sunday's surprise Premier Sports Cup defeat at Raith Rovers.
"Obviously the massive disappointment of Sunday is still there and it still bites," Glass said. "But it's important you focus on what's next and that's here and we're ready for it.
"Short term, what it offers the club in terms of revenue and the feelgood factor, right now, sitting here, it's the first thought on my mind.
"We knew it was a three or four-week process to get to the group stages if we could play well and fight well and that will finish next Thursday (in the return leg).
"It's a huge priority. I wouldn't say it's prioritised over the league or (domestic) cups, but from week to week the aim has been to win every game we go into. Right now it's our biggest focus."
Winger Jonny Hayes is hoping to recover from a foot problem in time, but midfielder Ryan Hedges has not travelled with the squad due to a hamstring strain. Glass has no other injury concerns.
The Dons manager said he was still hoping to strengthen his squad after the club had a bid reportedly worth £500,000 rejected by Hibernian for Australia winger Martin Boyle, who has signed a new contract with the Edinburgh club that ties him to the summer of 2024 and extinguishes any chance of him moving back to his hometown club.
Glass added: "The aim at the start of the transfer window was to come out of it stronger and that will continue to be the aim. That will be my response to that."
Meanwhile, Aberdeen chairman Dave Cormack has admitted the club’s wage bill will increase this season as they look to get closer to Celtic and Rangers.
Seven new players have been recruited this summer as Glass looks to shape the squad in his own image after being appointed successor to Derek McInnes towards the end of last season.
And Cormack wants to continue investing as he seeks to cut the gap at the top of the cinch Premiership table.
Cormack told the Unmodern Man: "Everybody knows the £60-80m a year that Celtic and Rangers are paying in wages and we’re certainly the third highest.
"As we mentioned before we started recording, our wage bill this season with the squad we’ve got is going to be higher than last season."