Did they keep some back for friends and family of the players and officials and for sponsors ? (which may be why there are always a few tickets that go on sale closer to the match day, as they may not then be wanted after all and then made available for fans to buy)
When I went to buy my tickets at around 10:30, there were 26 or so tickets left in block T, when i checked again at around 11, all block T seats had gone