Luke Modric is one of the all-time footballing icons, and the fact he is still performing at the highest level at the age of 39 is a testament to his professionalism. In most matches he plays, the midfielder is the oldest player on the pitch. However, that won’t be the case this weekend when his Croatia team take on Scotland in Zagreb. Former Celtic star Craig Gordon will hold that honour, set to take his place in Steve Clarke’s starting eleven after injury forced Angus Gunn out of contention. Gordon was already a 31-year-old veteran when he joined the Bhoys in 2014. He went on to make 242 app…