Celtic headed into a tricky away tie with St Mirren minus Matt O’Riley who was at Brighton finalising his £30m Premier League move. O’Riley is undoubtedly Celtic’s best player who has been at the heart of the team’s attacking threat over the last two seasons so the fans could be forgiven for looking at the St Mirren game with a hint of nerves. However, those nerves were calmed quickly after Callum McGregor and Reo Hatate put Celtic 2-0 ahead in the first half with Alistair Johnston sealing the three points with his first goal of the season to seal the 3-0 win over St Mirren. But it was Paulo B…