Sundgren began his university studies in Karlstad in the autumn of 2009 and played with various teams during this period. In the 2010–2011 season, he played with three separate teams. For the Elite Series, he skipped the Karlstad team vacated in 2008 by Oskar Eriksson, joining Oskar's brother Markus Eriksson, as well as Marcus Franzén and Henric Jonsson in forming Team Sundgren. He also skipped the Swedish team at the 2011 Winter Universiade, leading the team of Alexander Nordgren, Axel Rosander and Johan Spiik, though the team ended the tournament in 8th place. Sundgren skipped his own team, Lag Sundgren, for Karlstad in the Swedish Men's Junior Curling Championships, losing an extremely close final to his former teammates Oskar Eriksson, Kristian Lindström, Alexander Lindström, and Henrik Leek. He rejoined them for the 2011 World Junior Curling Championships, winning the gold medal. Though Sundgren was formally an alternate and did not play any games in the round-robin, he played the pivotal winning games in the semifinal and the final when Henrik Leek was under the weather and was essential to the gold medal victory.