Celtic through a bit of a curveball into the mix by producing a defensive masterclass against Atalanta in the Champions League on Wednesday night. It provides the whole club with a bit of a boost that they can compete with some of the best in Europe’s elite competition on the road. You don’t blame the Celtic fans for having a negative mindset in the Champions League after Brendan Rodgers watched his team concede seven to Borussia Dortmund last time out. But now, Celtic’s clean sheet against Atalanta has made things slightly interesting, especially with an away trip to Aston Villa in the pipeli…