First of all this would not happen because of the Nevada State Athletics Commissions states a fighter must wait 4 days between fights and must meet weight requirements. With that being said, I still think Matt Hughes could take it.
8-Man Openweight Tournament, Round 1:
Arlovski vs. Sylvia - Arlovski
Liddell vs. Ortiz - Liddell
Franklin vs. Silva - Franklin
Hughes vs. St. Pierre - Hughes
Arlovski would win, and even if Sylvia would win, he would just gas out in next round.
Liddell to KO Ortiz because Chuck has Tito's number
Franklin to win because he is the best Middleweight fighter in the world
Hughes would ground and pound GSP, this will be proven in a couple of months.
Arlovski vs. Liddell - Liddell
Franklin vs. Hughes - Hughes
Liddell would win mainly because he is more aggressive than AA.
Hughes would take a beating by Franklin but still win by decision.
Liddell vs. Hughes - Hughes
Hughes would win in my opinion because Liddell had tougher opponents. This would go to decision or doctor stoppage.
These are my opinions, so deal with it.