At the 2004 World MTB Orienteering Championships in Ballarat, Gritslan placed tenth in the middle, 32nd in the long, and sixth in the relay event.[7] At the 2005 World Championships in Banská Bystrica, he won gold medals in both the middle and long distances, and finished fourth with the Russian relay team.[8] In 2006, at the Championships in Joensuu, Gritslan won a bronze medal in the middle distance, a silver medal in the long distance, and a silver medal in the relay with the Russian team, behind Finland.[9] At the 2007 World MTB Orienteering Championships in Nové Město na Moravě, he won a gold medal in the long distance, placed fourth in the sprint, 57th in the middle distance, and fourth in the relay.[10] At the 2008 World MTB Orienteering Championships in Ostróda, he won a gold medal in the long distance and a silver medal in the relay.[11] In 2009, in Ben Shemen, he won a silver medal in the long distance, a bronze medal in the sprint, and a gold medal in the relay.[12] At the 2010 World Championships in Montalegre, he won a gold medal with the Russian relay team, together with Valeriy Gluhov and Anton Foliforov. He placed fourth in the middle distance, and tenth in the long distance.[13]
