Career
He is the older brother of fellow tennis player Mikael Ymer. Ymer made his Association of Tennis Professionals main draw singles debut at the 2013 Swedish Open where he lost in the first round to Grigor Dimitrov. Ymer received a wildcard at the 2014 Swedish Open defeating Mikhail Kukushkin in the first round before falling to João Sousa in the second round.
He qualified to the main draw of 2015 Australian Open after wins against Benoît Paire, January Mertl and Hyeon Chung.
He lost in the first round against Go Soeda in five sets. At the 2015 Barcelona Open Banc Sabadell, Ymer defeated Thiemo de Bakker and Nick Kyrgios to reach third round, where he lost to David Ferrer.
He qualified to the main draw of 2015 French Open after wins against Roberto Marcora, Blaž Rola and Roberto Carballés Baena. He lost in the first round against Lukáš Rosol in straight sets.
Ymer qualified to the main draw of 2015 Wimbledon Championships after wins against Thomas Fabbiano, Boy Westerhof and Guido Pella.
He lost in the first round to 23rd seed Ivo Karlović in four sets. Ymer successfully qualified for all four Grand Slams in 2015 after coming through qualifying at the 2015 United States Open. He lost in the first round to Diego Schwartzman.