Chelsea are on 9 points after four Champions League games so far. They are second in their group, 3 points behind Juventus.
Zenit are third with three points and Malmo are rock-bottom having failed to earn a single point in four games.
The Blues will go top of the group if they beat Juve by two goals (or a bigger margin) today.
If Chelsea beat the Italians by a one-goal margin, or the game ends in a draw, the Blues will qualify for the knockout rounds.
If Chelsea lose and Zenit fail to beat Malmo, Tuchel's side would progress to the last 16.
If Chelsea lose and Zenit beat Malmo, the Blues will remain second. But in this case, the second place would not guarantee last-16 qualification as Zenit would be just three points away from the Blues. In this case, Chelsea would have to get a draw or a win in St Petersburg on December 8 to advance into the knockout stages.
Champions League Group H standings after 4 games
1. Juventus, 12 points, +7 goal difference
2. Chelsea, 9 points, +5 goal difference
3. Zenit, 3 points, 0 goal difference
4. Malmo, 0 points, -12 goal difference.
