Chelsea face the prospect of falling six points behind Champions League Group E leaders Schalke should they lose in Gelsenkirchen tomorrow evening.
The Blues' shock opening match-day defeat to FC Basel left the door wide open for the Bundesliga outfit to seize the initiative, and they certainly have done.
In a group largely expected to be uncontested by Swiss giants FC Basel and Romanian club Steaua Bucharest, Schalke sit ahead of the second-placed Premier League side with six points ahead of tomorrow night.
Jose Mourinho should expect a difficult outing against Jens Keller's men and here are three on-pitch battles that could have a pivotal impact on tomorrow night's match.
Click through the tabs to see where the game is likely to be won and lost. Leave a comment with your thoughts.
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