City manager Manuel Pellegrini fielded a strong side as he looked to maintain interest in a competition won last year, but they were outplayed by an under-strength but determined Magpies team.

Goals from Rolando Aarons and Moussa Sissoko secured deserved win for Alan Pardew’s men, whose odds on victory had been 9/1.

Coming after a frustrating Champions League draw at CSKA Moscow and an unexpected Premier League loss at West Ham, the once free-scoring City are out of form as they prepare for a visit from their chief rivals on Sunday.

Montenegro international Jovetic said: “We need to be more determined and we need to score goals, because we are a team that scores more goals than everybody and when we don’t score we have problems.

“It happened last night. I hope the next game we will score again.

“We won this cup last year and we wanted to win it again.

“Unfortunately we didn’t make it but now we must forget, recover well and think about the next game.”

With one trophy option now gone, even at such an early stage of the season, the next week could be critical to City’s campaign.

They already trail impressive leaders Chelsea by six points in the Premier League and another loss to United could seriously damage their title defence.

That game is quickly followed by a visit from CSKA and anything less than victory in that game could leave them struggling to maintain interest in the Champions League. That in turn could put Pellegrini under the spotlight.

The Chilean had a night to forget against Newcastle. He made seven changes, leaving key men such as Joe Hart, Vincent Kompany and Sergio Aguero out of his starting line-up, but still sent out a strong team.

That not only backfired in terms of the result, but two of the stars who did start, David Silva and Yaya Toure, suffered injuries.

Silva is now a doubt for the derby after limping out of the action with a knee problem after just nine minutes. Toure was later withdrawn as a precaution due to a groin injury.

By the time Silva was taken off, City were already trailing 1-0 after the impressive Ryan Taylor, returning for Newcastle after two years out, robbed Fernandinho to set up Aarons.

City controlled possession as they sought a response and they went close on a number of occasions, not least when Fabricio Coloccini hit his own post.

But the hosts lacked intensity and, after being fortunate to escape conceding a penalty when Aleksandar Kolarov appeared to fell Gabriel Obertan, substitute Sissoko struck the killer goal 15 minutes from time.

Asked what went wrong, Jovetic said: “I think maybe the goal – they scored early. After that we tried, we played, we had some chances but we couldn’t score.

“At the end they scored a second goal. They deserved the win.”

Goalkeeper Willy Caballero, who deputised for Hart, was at a loss to explain the performance.

He said: “It was a really bad day for us. I don’t know what was missing.

“We had plenty of opportunities to score, but the last three matches have been the same. We have had no luck and no goals scored.”

Like Jovetic, the Argentinian also believes the United clash could offer the perfect opportunity to restore confidence.

Caballero, signed in the summer from Pellegrini’s former club Malaga, said: “It’s a big opportunity for us to change this. We need to recover, forget about this match and only think about United.

“It’s always a really, really big match. When I have watched these games from my house you can tell how big it is.

“For us it is a big opportunity, but we need a best performance from every player to win this game.”