Eight sides are already through to the last 16, led by holders AC Milan, the team they beat in last season's final, Juventus, nine-times winners Real Madrid and Manchester United.
But half the slots for the next round draw on December 12 are still vacant in what has been a tight qualifying campaign.
Nowhere have things been closer than in Group A, where Celtic, Anderlecht and Olympique Lyon all have seven points each and Bayern Munich are just a point behind.
Bayern, who won the last of their four European titles in 2001, have home advantage against Anderlecht while Lyon host Celtic at the Stade Gerland on Wednesday.
Group B is similarly wide open before Lokomotiv Moscow (8pts) head for Highbury to face an Arsenal side (7pts), who are back from dead after taking one point from their opening three games.
Former group leaders Inter Milan (7pts) travel in the opposite direction to take on Dynamo Kiev (6pts).
Monaco are already through to the next round from Group C but should at least get a point at winless AEK Athens.
Assuming they do, Deportivo would only need to avoid a 2-0 defeat or worse by PSV Eindhoven to join them.
Real Sociedad are at home to Galatasaray to decide who joins Juventus in the knockout stage from Group D and who joins all the other third-place finishers in the draw for the third round of the UEFA Cup.
DOUBLE ADVANTAGE
The Spanish club will have a double advantage, with both the crowd and a two-point lead over the Turks behind them.
Qualification from Groups E and F has already been decided with VfB Stuttgart and Manchester United meeting for first-place honours on 12 points apiece in the former, and Real in little danger of being knocked off the top by Porto in the latter.
Big-spending Chelsea (10pts) have already booked their place in the last 16 from Group G.
But Claudio Ranieri's men want revenge for a 2-0 defeat at Stamford Bridge against second-placed Besiktas (7pts) in a match which UEFA has switched from Turkey to Gelsenkirchen, Germany in the wake of last month's bombings in Istanbul.
Sparta Prague and Lazio, on five points apiece, can still hope for a victory in the Czech capital on Tuesday that could be worth a qualifying slot.
Holders Milan have already won Group H hands down and could afford to play a second string side against Celta Vigo (6pts) at the San Siro.
However, the rest of the group is wide open with second-placed Ajax Amsterdam (6pts) travelling to neighbours Bruges (5pts) in search of a money-spinning place in the next round.
