Roberto Mancini claims Manchester City’s FA Cup defeat by Manchester United earlier this year was the key turning point in their challenge for the Premier League title.

City lead their great rivals on goal difference at the top of the table with two games left, the first of which is a difficult visit to high-flying Newcastle United on Sunday.

Mancini’s team make the trip having beaten United at Eastlands to complete a rare derby double against the cross-city rivals they swept aside 6-1 at Old Trafford in October.

But it is the third-round FA Cup defeat by United, when captain Vincent Kompany was sent off in the early stages, that Mancini insists has instilled belief and resolve in the players challenging for City’s first title since 1968.

“The important game was the FA Cup when we lost 3-2 at home in January – not when we won 6-1 there, that was an easy game,” Mancini said.

“We lost 3-2 when we were down to 10 players after 10 minutes, but we recovered and had the chance to score the third goal.

“They didn’t have a shot in the second half with 11 players. That game was important. It changed our mentality against them.”

Mancini added that there was no need to give an inspirational talk in the dressing room before the recent derby victory game, which City needed to win to have a realistic chance of the title.

“Against United we knew it was the last chance for us,” he revealed.

The City manager insists also that the game at Newcastle, who are aiming for a top four finish and Champions League qualification, could be even more demanding.