Theres a couple potentially good matchups to be made. Kos vs. Diego would be sweet on a number of levels:
1) Their first fight on TUF was awesome. Non-stop.
2) Fighting Kos might make Diego a fan favorite for the first time ever, just b/c Kos is the dictionary definition of assclown.
3) Kos will come out looking like a cantelope used as a pinata.
Leben vs. Lister ..... naaa, that would probably suck unless Leben knocked him out while Lister walked around with his hands down b/c he was too tired.
Karo vs. Kos could be a good match too. I think Karo would take it. And once again, Kos would take a beating which I will never grow tired of watching.
Riggs vs. Kos might be interesting. I heard somewhere that Riggs is a wrestler, though he usually taps too quickly to display any of it. Either way Riggs may knock the bleach outa Kos's fro which would be both funny and past due.
Von Flu/Goulet is probably worse than Leben/Lister. I'm yawning thinking about it. Von Flu would flick him off and Goulet wouldn't understand what it meant.