Celtic are preparing to open contract talks with defender Alistair Johnston to tie him down to a new deal and make him one of the club’s highest earners. Johnston has been one of the team’s top performers in the first four league matches of the season, ranking highly amongst right-backs in the Scottish Premiership regarding percentage of tackles won, duel success rate, touches in the opposition box and creating chances. His combative, all-action displays up and down the right flank have made him one of the most important cogs in Brendan Rodgers’ Celtic machine. Now, the club are ready to rewar…