As of yesteday Milan still have 20,000 seats unsold for their game against liverpool (the biggest, bestest, most important and storied team in Europe).
The biggest home game of AC Milan's Champions League 'league phase' campaign, at least on paper, is Liverpool at home. Despite this, the club are having issues selling all of the tickets.
sempremilan.com
I hope UEFA and the clubs get a wake-up call, increasing the total group/league games from 96 to 144, to just eliminate 12 out of 36 clubs isn't very "box-office", some are charging premium prices for a routine enough qualification game.
Of the 12 teams to go out, you'd argue that the 9 below might be "shoe-ins". There's not huge jeopardy at the top tier level.
Clubs are asking supporters to pay £60+, plus travel and food and parking, on a mid-week night to watch a game in a largely "done deal" format..
GNK Dinamo (CRO)
Salzburg (AUT)
Lille (FRA)
Crvena Zvezda (SRB)
Young Boys (SUI)
Slovan Bratislava (SVK)
Sparta Praha (CZE)
Sturm Graz (AUT)
Brest (FRA)