Sander grew up in the Westphalian Ennepetal- Rüggeberg . He started skiing at the age of two under the guidance of his parents on the local Teufelswiese. He later traveled regularly with his parents for skiing holidays in the Alps. His talent showed up early on: He was multiple West German champion in his age group and German student champion in 2004. After the talent scouts of the German Ski Association (DSV) became aware of him, they brought Sander to Bavaria in 2004 to the Berchtesgaden Ski Gymnasium for optimal support . In autumn 2006 he switched to the Gertrud-von-le-Fort-Gymnasium Oberstdorf , which is a partner of winter sports.
The first successes quickly emerged. In 2006 he was four times German youth champion in slalom, giant slalom, super-G and downhill. In the following year he was vice youth champion in slalom and in 2008 he was vice youth champion in giant slalom. He celebrated his greatest success so far at the end of February 2008 when he won the gold medal in Super-G at the Alpine Junior World Championships in Formigal, Spain , the first world championship title for the DSV men's team since 2001. With this success he qualified for the World Cup final in Bormio . In his World Cup debut on March 13, 2008, however, he retired shortly before the finish.
In the following two winters, Sander was unable to confirm this success for the time being. He was mainly used in the European Cup, but was never better than twelfth. In the winter of 2010/11, however, he showed an ascending shape curve. On December 18, 2010, he finished 28th in the downhill run from Val Gardena , scoring his first World Cup points. There were also two podium places in European Cup races. At the 2011 World Championships in Garmisch-Partenkirchen , after finishing 21st in the Super-G, he suffered an inner ligament rupture in his right knee when he fell downhill. Five weeks later, he took part in the German championships on the same slope and won the downhill and Super-G titles.
The winter of 2015/16 proved to be particularly successful with six top 10 placements (two downhill runs, four super-Gs). On December 16, 2016, i.e. in the 2016/17 season , Sander celebrated his best World Cup result so far with fifth place at the Super-G in Val Gardena. At the 2017 World Championships in St. Moritz , he was 7th in the Super-G and 8th in the downhill. At the World Cup final in Aspen, Sander came in 6th in the downhill. The 2017/18 season was also very successful. In Kitzbühel he was sixth in the downhill and eighth in the Super-G. He qualified for the Olympic Games in Pyeongchang . There he was eighth in the Super-G and tenth in the downhill. After a mixed start to the season in winter 2018/19 , he had to end this early because, as diagnosed only after the races in Bormio , he tore a cruciate ligament in his right knee during training on the descent . Despite this injury, he still reached 14th place in the Super-G.