It is impossible for Russia to "lose" in Serbia. The vast majority of Serbs support Russia, and are pissed at their government for not supporting it enough.
It is very possible to juggle around with the opinions of "vast majority" like apples. Vast majority will always support the thing which a delicate minority will push into their throats via media.
Did I say otherwise? I think you meant to respond to the OP who implied that Russia is somehow "losing" because of these protests. My Russian wife is telling me that they don't like Vucic either and if he were to vacate the premises no one in Moscow would shed a single tear.