I wouldn't say it necessarily locks it up (much as I would like that - the 'UK' in my monicker is my country not my school, I'm a Duke alum...). But if Duke were to lose tonight I could see them slipping to a 2 if Vill thumps both the Friars and Hoyas and/or Arizona impresses in the P12T. While my old East Coast bias means I can't help but see Ariz and Utah as vastly overrated, for some reason they continue to get an undue amount of respect so if the Wildcats thump the Utes they could give the excuse the Committee needs to put a Western team in as West Region #1.
Don't get me wrong - I fully expect Duke to win tonight (their 30 pt whalloping of the Irish in Cameron means far more, IMO, than the 4 pt defeat in South Bend, especially considering the loss occurred in the midst of an eye-watering 5-game run of @ Louis, Home v Pitt, @ SJU, @ ND, @ UVa in which they won the other 4 games) but if they did lose you could easily make the case that they're behind UK, UVa and Wisc (assuming the Badgers win the Big10) and so would be up against 'nova and 'zona for the final #1 seed.