Manchester City Under-21s walked off during a friendly in Croatia after one of their players was allegedly racially abused by an opponent.
The game against HNK Rijeka was abandoned after the incident involving French midfielder Seko Fofana, who was sent off after an off-the-ball clash.
City said: "A decision was taken by the management staff to withdraw from the field and cancel the game."
The City team is coached by former France international Patrick Vieira.
A statement from Rijeka read: "Manchester City coach Patrick Vieira entered the field, something was discussed with the referee, and then to the amazement of a well-filled stadium he took his team off the pitch.
"What are the reasons? They are known only to him."
City added that club representatives are liaising with officials, the match organisers and the Croatian Football Association to pursue the matter further.
Manager Manuel Pellegrini, currently in Kansas on the club's United States tour, gave Vieira his backing.
"I don't know too much about what happened," he said. "But if Patrick took that decision I think it was correct because I am sure Patrick did the best thing. It is impossible to continue with those kinds of things during a game."
Fofana, 20, joined City from French club Lorient in 2013 but has yet to make his first-team debut.
Occasions when teams have walked off the pitch over racism are rare, with AC Milan's friendly at Italian lower division club Pro Patria in January 2013 the highest profile occurrence.
Milan's Kevin-Prince Boateng sparked the walk-off - and the end of the game - by picking up the match ball and kicking it into the crowd following racially abusive chants from the crowd.
In October, City midfielder Yaya Toure called for stronger action against racism after he was subject to chanting from CSKA Moscow fans.