I don't see an injury to RVP being in any way pivotal to their chances. It's just how they work. Rooney is barely scoring at the moment, but you just watch him start as soon as RVP is on the doctors table.
Chelsea I'm still really unsure of. Already had a bad little run and third despite starting the season much much better than us. Doesn't really tell you all you need to know though, farcical game against the shite, and their attack will overwhelm most teams in the league. Long term injury to Terry could be a problem possibly.
I've always maintained the Rags are our main competitors for the title and still think that. A lot seems to hinge on this possibility of Chelsea getting Falcao in January, which if they weren't in the race before that certainly would be after it.