Unger represented Germany at the 2008 Summer Olympics. In Beijing he competed in the 100 metres sprint and placed 4th in his heat behind Churandy Martina, Naoki Tsukahara and Simeon Williamson, normally causing elimination. However his time of 10.46 was the 10th fastest losing time, giving him a spot in the second round. There he improved his time to 10.36 seconds, but he was unable to qualify for the semifinals as he finished 7th place in his heat. Together with Till Helmke, Alexander Kosenkow and Martin Keller he also competed at the 4x100 metres relay. In their qualification heat they placed third behind Jamaica and Canada, but in front of China. Their time of 38.93 was the sixth-fastest out of sixteen participating nations in the first round, and they qualified for the final. There they sprinted to a time of 38.58 seconds, which was the fifth-best time.