Scotland go into their World Cup qualifier against Serbia tonight at the Stadion Karadorde without being able to call on the services of Robert Snodgrass. He was sent off for the penalty that allowed Wales to equalise last Friday night at Hampden and misses the game. Manager Gordon Strachan has called up Birmingham City's Paul Caddis as a replacement. Scotland are also denied the possibility of naming striker Steven Fletcher for the game after he was stretchered off in Friday's game with an ankle injury. Other squad members not travelling to Novi Sad yesterday were defender Russell Martin (hamstring) and Kris Commons (personal reasons).Manchester City full-back Aleksandar Kolarov is banned for the hosts, but they do have defenders Nenad Tomovic and Milan Bisevac back from suspension. Serbia lost 2-0 in Croatia on Friday and are fourth in Group A, with two more points than Scotland.