Spain, which came into the World Cup saddled with a tradition of choking, has shown that it wants to go far and has already qualified with the second round with convincing wins over Ukraine (4-0) and Tunisia (3-1). Even with reserves going, Spain should be able to take apart Saudi Arabia.
Ukraine recovered from its shellacking against Spain to apply its own shellacking to Saudi Arabia (4-0), which in turn announced that it will no longer export shellac. Ukraine will grab the second spot with a win or tie. Tunisia must win to advance and then hope that Saudi Arabia doesn't beat Spain by a ridiculous margin (which is likely.)
Saudi Arabia is still alive if it can beat Spain and the goal difference can be made up on both Tunisia and Ukraine.