Certainly one of the best matches of the early rounds this season, but overall it's probably still the semi-final of the International Championship between Williams and Allen. That was great drama, combined with a superb standard of play.
The other match that provided a big talking points was, of course, Barry Hawkins vs Nigel Bond. I watched frame 5 and 6, and at 5-1 thought that Hawkins was going to win it eventually, and couldn't be bothered to watch the formality of it.
I could work for the BBC commentary team with expert opinion like that.