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Attack: Clint Dempsey, Jermain Defoe, Gareth Bale
Aaron Lennon is also a doubt for Wednesday's game. Even if he is fit enough to feature, there is an argument that Spurs would benefit having him as an option off the substitutes' bench.
We do not know if Villas-Boas intends for his team to really take the game to Chelsea, or approach his former club more cautiously. Given the midfield possibly being without both Parker and Dembele, having Clint Dempsey in the side gives Spurs room to maneuver.
Dempsey is able to drop back and help his midfield if they find themselves under siege for a sustained periods of play. The American also offers a genuine goal threat, something he has proven throughout this season in big games versus Manchester United, Basel and Manchester City.
Emmanuel Adebayor performed decently after coming on against Southampton. But Jermain Defoe deserves to stay ahead of him up front for a few reasons.
Defoe, to be frank, works a lot harder. Spurs will need him to put the running in that might catch a David Luiz or Branislav Ivanovic off guard as they seek to apply pressure to Chelsea. Obviously there is the striker's goal threat too.
He also gives Villas-Boas some flexibility in how he might use Gareth Bale.
The Welshman's recent goals have come from him operating from right wing, but he has not always been able to involve himself as much as he might like there.
Should Villas-Boas want to deploy Bale centrally while still maintaining a primary front three, Defoe can be moved out wide and asked to cut in from there.
As has been the case this season in some of Tottenham's best wins (the move to 4-3-3 during the 3-1 over Man City being a big example), adaptability on Villas-Boas' part could be key. Spurs will hope there is plenty of back and forth in this game, as that would mean they are giving Chelsea something to think about.
If they are to get the win (heck, even just avoid losing) they will have to overcome a team full of confidence—not to mention historical disadvantage. Its not going to be easy, but if Spurs want more meaningful occasions such as this, they are going to have to get used to such challenges.