Edin Dzeko grabbed the only goal of the game as Bosnia and Herzegovina overcame Austria 1-0 in Zenica to take control of Group B3 in the Uefa Nations League.
The Roma striker netted his 53rd international goal 12 minutes from tome to make it two wins from two for Robert Prosinecki's men, putting them in pole position.
Northern Ireland face Austria next month, with both sides aiming to pick up their first points of the campaign after defeats to the Bosnians.
Meanwhile, World Cup runners-up Croatia were thrashed 6-0 by Spain in their extraordinary Nations League opener in Elche.
Romelu Lukaku scored twice as Belgium cruised to a 3-0 win over Iceland in Reykjavik.
In League C, Hungary edged a 2-1 win over Greece in Budapest, while Finland maintained their promising start as Teemu Pukki's 12th-minute effort proved decisive in a 1-0 victory over Estonia.
In League D, Luxembourg eased to a 3-0 win in San Marino, while Moldova and Belarus drew 0-0.