I think we may actually see the same defence that started at Villa, meaning arbeloa will get the nod at left back with Riise playing as a left winger again, I can't see Babel starting, although he looked pretty good against Toulouse, I don't think Benitez wants to take too many risks in such a big game.
I'd like to see Pennant start on the right, love him or hate him he's our best option there at the moment with Gerrard taking the central role, I think Pennant played pretty well against Villa, he got into space, tried to create opportunities and worked hard for the team, Rafa may prefer Benayoun there but I don't think he played well at all against Toulouse, he never really got into the game and I don't think playing on the right is his best position, he may struggle there.
I think we should go with Mascherano next to Gerrard rather than Alonso, this is because we will need to keep it tight at the back and make it hard for Chelsea to find space, if Gerrard is roaming forward, Mascherano will be there to track back, and help out the defence when he can, Alonso can't do this as well and I think Masch will handle the physical side of the game better.
Up front,Torres is a must, he adds a huge threat to Chelsea's defence (hopefully without Terry) and I'd play Kuyt alongside him to try and develop that partnership, it looked fairly good at times against Villa, I think if these two get used to each other's games then it could be very effective.