Celtic were left frustrated after they let a two-goal lead slip to draw 2-2 against Aberdeen at Parkhead on Saturday. Aberdeen are challenging Celtic for the Premiership title, how long that lasts remains to be seen, but so far, they are a huge threat and Brendan Rodgers has something else to think about. Just maybe, he would have been expecting Rangers to be knocking on the title door or even lurking around the corner. But Rangers’ defeat to Kilmarnock on Sunday means that they are now six points behind the top two. Before a ball was kicked in Paradise, many were hoping for the table – seven …