You gain nothing by knowing that a couple of minutes before the fight. You'll know I'm left handed almost immediately. I gain nothing by faking with my less dominant hand, because it just delays me from getting the grip I actually want. You'll try to stop me turning into the right, which is fine, because I love my lapel side Seoi and my Sode. If you can out gripfight me and prevent me getting a grip - well done - you are a much better judoka than I am, but realistically, the second you take my lapel, I'm going to take yours. The best you can hope for is preventing me from getting the inside grip. But it's ok, I have a lapel side drop seoi that works from the outside. There are a thousand ways to best your opponent in Judo - knowing whether your opponent is a lefty or a righty 2 minutes before your match isn't one of them.