Manuel Pelligrini's side are now six points behind leaders Liverpool with just one game in hand after they failed to beat a side seemingly destined for relegation.

And it could have been worse, as two goals from Connor Wickham threatened to hand City only a second home defeat of the season, until Nasri saved face at the death.

City went ahead after just two minutes through Fernandinho, but following Wickham's late brace, they were indebted to a howler from Sunderland goalkeeper Vito Mannone, who fumbled Nasri's 88th-minute shot over the line.

City had wasted no time in looking to close the gap on Liverpool as they went ahead with their first attack at the Etihad Stadium.

Pellegrini had made five changes -- some enforced, some tactical -- to the side beaten 3-2 at Liverpool on Sunday and the reunited strikeforce of Sergio Aguero and Alvaro Negredo was key to the hosts' flying start.

Aguero's pass, after Lee Cattermole had tamely surrendered possession, was cleverly dummied by Negredo for Fernandinho to run through and steer a shot past Mannone at his near post.

For a side bereft of points and confidence, it was the worst possible start, and Sunderland must have immediately feared the worst.

But they did not buckle, and created a flurry of chances to wrest the initiative away from a City team missing injured playmaker David Silva and midfield powerhouse Yaya Toure, and seemingly seized by complacency.

England goalkeeper Joe Hart almost gifted the visitors a route back into the game with a terrible clearance that would have given ex-City winger Adam Johnson an open goal had his control been better.

- Cutting edge deserts City -

Captain John O'Shea should then have headed in a Sebastian Larsson free-kick, which he directed just wide, before the former Manchester United defender headed another Larsson set-piece over the top.

At the other end, Mannone made hard work of dealing with an Aguero shot, with Fernandinho almost following up to score, but that was an isolated incident as Sunderland continued to press for an equaliser.

And it should have come after 18 minutes when Fabio Borini was given the freedom of the City penalty area, but lacked the composure to make it count as he dragged a weak shot across the face of goal.

City struggled to make anything like as good a chance for the remainder of the first half and after having a shot blocked by Cattermole 10 minutes into the second half, Aguero was replaced by Stevan Jovetic.

Jovetic did at least test Mannone with a low curling shot, before sending an acrobatic volley over the bar from Nasri's free-kick.

And Pelligrini then showed his hand again by sending on Edin Dzeko for the tiring Negredo, in an attempt to find a second goal and earn some much-needed breathing space.

Any thoughts that that would materialise quickly disappeared, though, as Sunderland finally got the goal they deserved to level the scores with 17 minutes to go.

It took a decent save from Hart, spreading himself to thwart Jack Colback, to keep the Black Cats at bay initially, but within 60 seconds they were attacking down the opposite flank to force the opening.

Substitute Ignacio Scocco made the decisive run and when he fired the ball across the face of goal, Wickham timed his arrival perfectly to side-foot home a volley from six yards out and claim his first league goal since October 2011.

He did not have to wait long for his second, superbly drilling home an angled drive from Emanuele Giaccherini's pass to seemingly wreck City's title dream.

Nasri spared City's blushes when Mannone spilled his shot over the line, but the French midfielder should have won it moments later with an effort that he lifted over the bar.