City have now lost 1-0 at the Stadium of Light for a third season in succession, after Sunderland goalkeeper Simon Mignolet made a string of impressive saves to preserve his team's narrow advantage.

The defeat, coupled with Manchester United's dramatic 4-3 win over Newcastle, leaves Mancini's side seven points adrift in the title race, leaving the Italian manager bewildered at his misfiring strikeforce.

He told BBC Sport: "Next year we won't come. We won't spend the money to come here. But in the end we won the title (last season).

"We didn't deserve to lose, we dominated this game, I don't know how it's possible that we didn't win this game, but every year it is the same.

"I'm frustrated at this because it's impossible that our strikers don't score, but we have this problem, we don't score enough to win the game. This is a big problem at the moment."

Pablo Zabaleta appeared to be fouled in the build-up to Adam Johnson's goal, and Mancini criticised referee Kevin Friend and his officiating team for their overall performance.

"Maybe Zabaleta deserved a red card," Mancini sarcastically joked.

"I don't think the referee and the linesmen had a good performance today."

Sunderland manager Martin O'Neill hailed his team's latest upset victory over the title holders.

"It was a great day, a great performance and to beat Manchester City was a big, big result for us," he told Sky Sports.

"They are champions of England and they are a really fine side, a fantastic side and early in the game you expect them to come into it and we fought off that challenge and came into game ourselves and scored a goal and created some great chances."