Nicolas Kiefer (; born 5 July 1977) is a German former professional tennis player. He reached the semifinals of the 2006 Australian Open and won a silver medal in men's doubles with partner Rainer Schüttler at the 2004 Athens Olympics. Kiefer's career-high singles ranking was world No. 4, achieved in January 2000. Tennis career 1995–2005 Kiefer was taken notice of as an outstanding junior. He won the Junior Australian Open, the US Open, and was a finalist and semifinalist at Wimbledon and the French Open finishing as the No. 2 junior behind Mariano Zabaleta when he was 18 in 1995. On 10 January 2000, he reached his second quarterfinal at the Australian Open and afterwards was ranked world No. 4, his highest position. Kiefer was known to have some tennis superstitions. He was sometimes seen tapping his racquet on the corners of the court after a point, and, when serving, frequently asked for the ball with which he had just won a point to re-use it for the next one. 2006–2007 Kiefer became infamous for an incident on 25 January 2006, during the quarterfinals of the Australian Open. While facing Sébastien Grosjean late in the fifth set of a marathon match, Kiefer threw his racquet midpoint. Grosjean lost the point, hitting the ball into the net. Grosjean protested that the racquet distracted his shot. The umpire Carlos Bernardes said he did not believe the act was intentional and noted Grosjean had already hit the ball before the flying racquet could have had any effect on his shot. Grosjean eventually lost the fifth and final set to Kiefer. Kiefer went through to the semi-finals where he was defeated by the 2004 champion Roger Federer. Kiefer injured his wrist while playing at the 2006 French Open, and announced his return on 5 July 2007, having fallen to the 404th position on ATP. He announced that he was "tired of waiting and anxious to start traveling again and to see his name on scoreboards". Kiefer returned at the 2007 Gerry Weber Open, losing in the first round to eventual champion Tomáš Berdych. At Wimbledon, he made the third round after defeating No.30 seed Filippo Volandri and Fabrice Santoro, both in straight sets, before losing in 4 sets (3 of which were tiebreakers) to Novak Djokovic. At Newport, however, he ended up losing in round 1. At Los Angeles, he reached the semifinals in