The Viola are one of the teams to watch this term and are gelling surprisingly quickly with their new signings.
Dogan Sahin failed to make the most of a Nenad Tomovic error in defence before the break.
Moments later Ljajic was again the creator, as his free kick was floated on to the head of Massimo Ambrosini.
It was a friendly, but Gaziantepspor went down to 10 men following a second yellow card for Kecojevic. Nonetheless, they got one back with Tosun’s penalty after Marcos Alonso’s foul.
Ljajic did get his goal in the end, running on to an Alonso backheel flick to burst through the Turkish defence.
Vecino rounded out the scoreline in the final minutes with an angled drive.