I think it's too early to put any predictions yet, because all depends on injuries, form, new signings and other factors. But Sevilla, Bordeaux, Barcelona and maybe Real look certain for the next round. Bordeaux won twice over Bayern and totally outplayed Juventus, have a magnificent run in France, so I can see them winning over Olympiakos. Sevilla shouldn't be troubled by CSKA, especially when two of their key defenders, including the skipper Iganshevich are suspended. Stuttgart are having tough times in Bundesliga, Lyon too, and the quality of the Spanish giants is enough to see them off.
If Robben and Ribery are fit, then Bayern will be a high mountain to climb. Not that Fiorentina won't have their chances, but the Bavarians are the more experienced and the better team.
The other 3 ties are highly unpredictable.
I must say that United and Chelsea look stronger right now, but everything can happen in these games. Porto may beat Arsenal, actually I like Hulk very much, and will be happy to see him celebrating.