Celina is on a season-long loan at Dutch club FC Twente, and the midfielder's performances for the club have sparked Dortmund's interest.
Matt Jurman could well have left Sydney FC during the A-League preseason but he chose to stay.
Talks are taking place over an international league involving the biggest clubs in Scandinavia, Scotland, the Netherlands and Belgium.
City are now managed by Pep Guardiola, who worked under the Netherlands great for eight years at Barca.
many players from Barcelona are coaches right now. His influence on us was outstanding, amazing, huge," Guardiola said of Cruyff.
FIFA said 21-year-old Arber Zeneli can switch from Sweden, where he was born and represented at youth and under-21 level.