From 1956 to 1979, the Soviet Union and Yugoslavia contested friendly team chess matches on an almost annual basis, with the venue alternating between the two countries.
[1][2][3] Only men participated in the first three matches, but afterwards women and boys were often included on the teams as well.
Nevertheless, the rivalry between the two countries turned out to be one-sided: all 21 of the matches were won by the Soviet team.
[4] The Soviet Union and Yugoslavia stopped contesting regular matches after 1979.
However, their friendly rivalry was rekindled in 2007, long after both countries had ceased to exist.