Not since 1985 have the #2, #3, and #4 teams all lost on the same day. I watched #3 Clemson lose to Pittsburgh, then later watched #2 Michigan lose to Iowa. #4 Washington lost to #20 USC.
Now that Alabama is the only undefeated top 10 team, we are guaranteed to have several 1-loss teams in the playoff, possibly even a 2-loss team by the time conference championships are over. Who do you think will make it now?
Personally, after watching Louisville play several times this year, I think they match up best against Alabama. But they did lose a close game at Clemson, so I doubt they would leapfrog.