Tszyu by mid to late rounds stoppage. Hatton would have some success and make things uncomfortable for Tszyu, but a younger Tszyu was quicker and sharper. He'd more often catch Hatton coming in with that laser right hand, and Tszyu was also no slouch to the body as well. Eventually Tszyu would be too much for a game Hatton.
Hatton always is hard for Tszyu...and that wasnt a shot Kostya in there against Ricky, just a fading one. But prime Tszyu has that extra quickness, reflexes and strength that lets him get off his shots better. He probably stops Ricky.
If Hatton doesn't have Dave Parris fighting alongside him, Tszyu wins, regardless of whether he's in his prime or not.