Career
He ranked near 1 player in the Netherlands and reached Association of Tennis Professionals singles world ranking near 100 by June, 2006. In 1998-1999 he comprised the Jong Oranje - a prized contract presented by the KNLTB to Netherlands" most proficient junior players. During a Mauritius Challenger tournament, late in December 2004, he was tested positive for a metabolite of cannabis or tetrahydrocannabinol (THC).
Whilst the Association of Tennis Professionals tribunal accepted Van Gemerden had committed a doping offense under the rules of the Tennis Anti-Doping Program with Exceptional Circumstances.
The use of cannabis, in that case, was determined to not be for performance enhancing reasons. Although he was eligible to return to competition immediately, Van Gemerden voluntarily sat out.
Coming after, in July 2005, he defeated Kristof Vliegen, triumphing the Scheveningen Challenger. He took on Slovakia in the 2005 World Group quarter-finals and appeared both in the doubles, with Paul Haarhuis, and in the singles against Michal Mertiňák.
The same year, he was a quarter-finalist in the 2005 Dutch Open, beating world number 46 Christophe Rochus en route.The following year, in 2006, he played in both the French Open and Wimbledon Championships.
In France he lost in the opening round to Juan Mónaco but he made the second round of Wimbledon, beating Josh Goodall, before being eliminated from the tournament by Mardy Fish. Van Gemerden made it to United States OPEN by 2008, being defeated by Jean-Yves Aubone at the first round. Postliminary, in 2008, he began professionally coaching Ana Ivanovic, then ranked near
5 of the Women's Tennis Association Tour.
Van Gemerden carried as a professional tennis coach until November 2015, instructing the likes of Fernando Verdasco, Sorana Cirstea, and Thiemo de Bakker. Singles: (1)
Doubles: (3).