Santos easily. He is underated, and under appreciated IMO. His biggest problem is not being active enough, but unless he's aged big time since his last fight, he'll have too much for Foreman. Probably a later round TKO.
Last time I recall all the undercard fights ending early, HBO had to resort to running a short documentary on Michael Buffer because they can't start the main event until a certain time. That was during Trinidad-Wright, I believe. So I'm hoping Soto-Karass/Gomez and Chavez Jr./Rowland go some rounds. As far Santos-Foreman goes? I hope it ends as quick as possible, or else we'll certainly be bored to tears. Santos can whack, so maybe he'll catch Yuri early to spare us. Or hell...even a no contest due to accidental headbutt would be good.
Santos will catch Yuri the same way he caught Alcine. The only difference is, I won't be making as much money on this fight as the Alcine-Santos fight because Daniel isn't an 8-1 underdog in this one...unfortunately.