AFC Ajax and Arsenal FC are in the driving seat but any two of four Group B sides can qualify on Wednesday.
All to play for
Qualification - and the associated rewards that come with it - is still possible for both Newcastle United FC and Internazionale FC in Group A and all four clubs in Group B where only three points separate leaders AFC Ajax from fourth-placed AS Roma.
Race for second spot
With FC Barcelona already qualified from Group A, third-placed Newcastle must win at home to the Spanish side and hope that second-placed Inter fail to beat the eliminated Bayer 04 Leverkusen in Germany. Internazionale could afford a draw or even defeat as long as Newcastle do not win.
Draw sufficient for Ajax
Ajax will go through tonight if they win or draw away to Roma; they will also qualify if they suffer a single-goal defeat of 3-2 or more and Valencia CF are beaten by Arsenal FC, the other two teams making up the group.
Four teams could qualify
In the case of second-placed Arsenal, the English champions will progress either if they win or draw in Valencia, or if they lose and Ajax also lose. For Valencia, a point below Ajax and Arsenal, it is more simple: Rafael Benítez's men must beat Arsenal, as any other outcome will not be enough. Roma, meanwhile, will advance if they win against Ajax and Valencia and Arsenal draw; or if they win 1-0 or 2-1 and Arsenal win.
So, elimination or qualification is a complicated matter and as kick-off draws near coaches and managers of the teams with a chance of progressing will be dusting off the calculators while praying that results elsewhere conspire to give them hope.