Commentary for Avodah Zarah 142:6

Again, we reject the previous conclusion. The purchaser does acquire the wine as soon as it is put into his jug. And still the wine becomes nesekh before it hits the bottom because there might be a little bit of wine belonging to the non-Jew left over in the vessel into which the Jew pours his wine. As soon as the Jew’s wine hits this wine, it becomes nesekh, even before it is acquired by the non-Jew.