On a tough night at the very start of a new season, against a dogged Dundee, it was a familiar name that helped Celtic usher in victory. The left-back has arguably been Celtic's best player since the return of Martin O'Neill in January, but his renaissance has gone a little under the radar. Perhaps that's because we expect so much from the man who once fetched Celtic a reported £25m in a move to Arsenal. Regardless, he still registered 12 assists last season, the most of any Celtic player, and scored six goals from defence. One of O'Neill's most trusted lieutenants, he's contracted until 2030 but reports have suggested a potential return to Spain, so just how important is he to Celtic?