I don't think he'll play a "weak" side as he'd get slaughtered if they got beat and then got dumped out of the CL anyway.
We'll see mainly his strongest side, with a few players starting by default due to not being available for Atletico (e.g. Lampard, Mikel).
He'll also set-up very defensively (similar to today) based on the fact that its what he's done away from home against any decent side this season and it'd be pretty stupid to try go toe to toe with his current side. He hasn't really changed from the manager 9 years ago who negated the threat of the best attacking players he's had in a Chelsea side, all in order to nullify an attack spearheaded by Milan Baros.
Cech out, Terry possibly out, Ramires probably out, Hazard/Eto'o either partially fit and playing or not playing at all, whilst they still have an eye on the second leg and knowing that even if they beat us they're unlikely to win the title should hopefully make this a little more comfortable than the Man City game.