Most of the 16 places in the first knockout round of the Champions League could be known after the fifth matchday of the group phase of the competition is completed this week.
With four of the six matchdays played Chelsea, Inter Milan, Juventus and Olympique Lyon are already assured of their places in the next stage.
They could be joined by as many as 10 other clubs if Tuesday and Wednesday's matches go according to form.
The two groups that will still be unresolved no matter what happens this week are Group H and Group B.
Group H has already been won by Chelsea, but has a three-way fight for second place between CSKA Moscow, Paris St Germain and European champions Porto and can only be decided after the last round of group games next month.
Group B, which includes nine-times European champions Real Madrid, will provide at least one definite qualifier if Real beat Bayer Leverkusen on Tuesday.
However the complicated mathematics involved in the group which has Dynamo Kiev, Real and Bayer Leverkusen all on seven points and AS Roma on one, mean that the second qualifier will only be known after the last matches on December 8. However, if Real win, they are certain of their place.
The other complication in the group has nothing to do with football, but Dynamo's match with Roma could be postponed because of political tension in Kiev following last week's General Election there.
Real however, will be concentrating on bouncing back from their 3-0 drubbing by Barcelona in La Liga on Saturday and it could be a landmark day for Real striker Raul who needs just one goal to equal the all-time European Cup scoring record of 49 goals established by Real legend Alfredo Di Stefano 40 years ago.
FERGUSON LANDMARK
Tuesday will also be an important day for Manchester United boss Alex Ferguson, whose team will make sure of their place in the next round with one match remaining in Group D if they beat Olympique Lyon at Old Trafford.
Ferguson, whose first match in charge of United ended in a 2-0 defeat at Oxford United on November 8, 1986, takes charge of the team for the 1,000th time on Tuesday.
He will be looking for an improvement on their 2-2 draw at Lyon in the opening match of the series when Ruud van Nistelrooy scored twice to salvage a point after Lyon went 2-0 up.
If Sparta Prague win or draw against Fenerbahce in the other match in the group, United will actually qualify for the next round no matter the outcome of their match against Lyon.
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In Group C Juventus have already sealed their place after four straight 1-0 wins and Bayern Munich will join them if they beat Maccabi Tel Aviv as expected and Juventus see off Ajax in Turin.
With Chelsea already qualified and Liverpool and Manchester United hoping to come through on Tuesday night, Arsenal will aim to become the fourth English club to qualify on Wednesday.
But they face a worrying match against Group E leaders PSV Eindhoven in the Netherlands.
PSV lead with nine points, followed by Arsenal (6), Panathinaikos (5) and Rosenborg Trondheim (1).
FALTERING ARSENAL
Arsenal have faltered in the Premier League in recent weeks winning just once in five games, and their performances in Europe have been almost as indifferent.
They need to re-discover the kind of form that gave them a 4-0 win at Eindhoven two years ago, but if they were to lose on Wednesday and Panathinaikos beat Rosenborg in Norway, Arsenal's fate would be out of their own hands.
A win for PSV will put them through. If Arsenal win and Rosenborg beat Panathinaikos, then PSV and Arsenal would both be through.
Group F, which is all but decided, will definitely be over if Barcelona beat Celtic at the Nou Camp and AC Milan see off Shakhtar Donetsk at the San Siro.
Milan and Barcelona both have nine points, Celtic and Donetsk both have three and in reality the focus now is on who finishes third out of Celtic and Donetsk to take the UEFA Cup place.
The one vacant spot in Group G will be taken by Werder Bremen if they become the first team to beat Inter Milan, who have already qualified. But if Werder lose and Valencia beat already-eliminated Anderlecht, the outcome of the Valencia-Werder match in Spain on December 7 will decide who qualifies.
Chelsea wrapped up their place when they won at CSKA Moscow on November 2 for their fourth successive victory -- leaving the rest of the group trailing in their wake.
But although CSKA and Paris St Germain only have four points, and Porto only have two, all three clubs are still in the hunt for second place.
If CSKA beat Porto in snowy Russia and Chelsea beat PSG, second place will be decided when PSG play CSKA in Paris on December 7. If PSG better CSKA's winning 2-0 margin in September, they will go through.