As you can see, the probability of Chelsea winning is estimated at almost 50%, which should be very strange for teams with such different value of squad and expenses. By the way, +93% in a home game looks very tempting, but when Chelsea is in business, you don’t want to take risks even for such a profit 
Because they think when the match is happen in own home, there's a good chance the home's team will win, but Nottingham were able to beat Chelsea in Stamford Bridge is really mind blowing lol. Although Aston Villa were not good like the last season, but they're better than Notthingham Forrest.I believe Aston Villa will able to beat Chelsea.
I'm biased towards Aston Villa (their degenerate goalkeeper annoys me), but I wouldn't say Aston Villa performed poorly last season. They finished in 7th place, which may seem like a bad result, but they made it into the European competition, plus if we look at which clubs were ahead of them, I would call it a success. In fact, Aston Villa was able to beat all the opponents that were within their capabilities, and even some elite ones (Chelsea, Tottenham).