Fulham striker Aleksandar Mitrovic scored twice as Serbia beat neighbours Montenegro in a historic first meeting between the former Yugoslav republics.
The two nations, who competed as one at the 2006 World Cup finals, became independent nations later that year.
Although played under tight security, the Nations League third-tier match had a friendly atmosphere.
Mitrovic sent goalkeeper Danijel Petkovic the wrong way with an 18th-minute spot kick and hit a right footed shot from very close range into the bottom left corner of the goal for his second.
Serbia next visit Romania while Montenegro are at home to Lithuania on Sunday.