Sydney FC's revolving defence irks Nikola Petkovic Hole in the wall: Nikola Petkovic (left) is searching for another partner in the centre of Sydney FC's defence. Sydney FC central defender Nikola Petkovic is frustrated with the constant upheaval along the back line as he prepares to forge his third central defensive partnership in just seven A-League games. The Serbian defender has been the only constant figure in the heart of Sydney's defence, and will likely play alongside his third companion this season, Matt Jurman, against Melbourne Heart on Friday night due to suspensions. The two-match ban of Petkovic's recent partner in defence, Tiago Calvano, and another one game suspension for left back Marc Warren forces two changes on coach Frank Farina for Sydney's clash against the Heart. Brazilian centre-back Calvano received his ban from the Match Review Panel for an off-the-ball foul on Melbourne Victory striker Archie Thompson during the Sky Blues 3-2 win on Saturday night, and also faces a potential season-ending ban for another incident in that game. He is also suspended for this [foul on] Archie Thompson. He kicked him; it happens in football. It's not easy for us, we started to play three games together. I first played two games with Seb Ryall, now with Tiago and now I have to change my partner," Petkovic said. The former Red Star Belgrade player laments the heavy toll the forced rotations have had on the stability of his club's defensive combinations. "This [stability] is the best way, and if you play every week with the player and your partnership is the same, but now the situation has change, he is suspended," Petkovic said. Calvano will likely learn his fate next week when the Match Review Panel decides the length of his suspension for his physical altercation with Green. There are fears within Sydney's camp that the Brazilian might have played his last game for the season already, given the precedence of a nine-month ban given to former Central Coast Mariners goalkeeper Danny Vukovic in 2008. When you touch referee, maybe your season is finished. It's not easy but I support him and I wish him all the best," Petkovic said. What can he say? He didn't want to touch the referee but he just wanted to help his team, at the moment that was the situation. Despite the instability of the starting line-up, the Sky Blues travel to Melbourne with a sense of relief having ended their three-match losing streak with a brave win over the Victory last Saturday. Playing for more than an hour with only 10 men, Sydney showed courage to hold on to a slender win, and that fighting mentality has been at the forefront of their preparations this week. "We're very happy about this, and we need to keep this for next Friday to take another three points," Petkovic said. Of course, it's not easy because Sydney is the biggest club here, and we lose three weeks, but now the atmosphere is better, we feel better and this is good for us.