A resounding victory coupled with a first clean sheet of the season will be music to the ears of Manchester City manager Roberto Mancini- so after an indifferent start to the defence of their Premier League title, are the champions now back to their scintillating best?

After being outclassed by the silky, sublime and slick football of Bundesliga champions Borussia Dortmund in the Champions League in midweek, it was important for City to return to Premier League action with three points against a Sunderland side who have never won away to City in the Premier League. Sunderland took four points off City last season- a 1-0 victory on New Years Day at the Stadium of Light- which sought to hamper their chances of challenging United at the top therefore they are a team not to be taken likely. The fact that City swept them aside in the manner they did sends a moderate if not serious statement of intent to the rest of the contenders. They expressed signs of significant improvement which bodes well in terms of climbing the table while their plan for the season as a whole is starting to take shape. Big players are beginning to perform.

It was particularly vital to keep the pressure on their rivals but when coming into the game they had won only one of their previous three league encounters. Joe Hart was outstanding in the 1-1 draw with at least seven outstanding saves keeping his team firmly in the game and keeping the Germans at bay.

However, ironically he had little to do against the Black Cats yet ended the match with his first clean sheet of the campaign and his 50th shutout in the Premier League. It has taken seven league games which sparked the alarm bells ringing and has highlighted the laborious start that the Etihad club have made this term but what are the reasons behind this distinct failure to prevent opponents from finding the net? Naiviety, complacency or underestimation of opponents. It is difficult to outline- only the players and staff alike really know the true answer yet we can speculate that there has been unrest behind the scenes.

In a title winning season built on a solid defence in 2011-12, City had surprisingly leaked goals in every match in every competition so far which had posed a serious question regarding their fight for this year's coveted prize. Last season's extraordinary title success was built on a settled back four and the blossoming partnership developed between captain Vincent Kompany and Joleon Lescott who were the mainstay of the defence and left experienced campaigners such as Kolo Toure kicking their heels on the substitutes bench.

With the skipper absent with a calf problem, Lescott- who netted in his previous game against Arsenal- came back into the fold while Micah Richards returned from injury to make his first start of the season. The athletic defender stepped into the breach and filled the void in a professional manner. Having only been told he was going to play on th morning of the game, Richards looked fit, determined and ready whilst playing with a smile on his face. Brought through the Manchester City ranks from a young age, he is now one of a small collection of players who has remained with the club throughout its glamorous transition period during the last four seasons which has seen the club transformed from a top ten Premier League side to one challenging for the major football honours.

Following the glittering arrival of the ageing Maicon in the summer transfer window combined with the fine form of Pablo Zabaleta, Richards is likely to have a difficult challenge to regain his regular starting position in his favoured right-back berth therefore his return to action in a central role may well be a change that Mancini is seeking to make on a more permanent basis and convert the Englishman into the next best centre-back. His strength and aggression on the ball are key factors that he possesses- the perfect characteristics required from a traditional central defender. The fact that he managed to keep one of the Premier League's hottest strikers, at present, quiet in Steven Fletcher speaks volumes.

It took a late Mario Balotelli penalty to salvage a vital European point on Wednesday however his contribution to the Sunderland win was scarce. Elements of his old ways appeared from the cracks- complaining to referees, shrugging his shoulders and missing chances. Another moment which summed up his match occurred when he was caught three yards offside. The camera panned straight to Mancini and David Platt who were gesticulating in regards to what to do next. Just seconds before his departure, he wasted a glorious opportunity to change the manager's thinking and get a goal for himself when he failed to connect with a stupendous left-wing cross from the impressive Aleksandar Kolarov. The Italian eventually left the pitch ten minutes after half-time to be replaced by Sergio Aguero with his normal antics returning as he walked down the tunnel.

Although, the introduction of the Argentine made a slight difference as the forward made an almost immediate impact by bagging himself a first league goal of the campaign- the first since firing at the same end against QPR to clinch the Premier League title in May. His performances and goalscoring will be absolutely crucial in the coming weeks if City's season is to be uplifted. His goal was beautifully taken while City looked more menacing and threatening on the attack in the last half an hour when he was on the field.

Mancini was first to criticise the schedule which saw his side be the first to play this weekend in the Saturday lunchtime slot straight after a Wednesday night kick-off in Europe, however, the strength in depth at his disposal allowed him to make wholesale changes to the team and it paid dividends as a fresh looking City side saw off Sunderland with no issue whatsoever and no questions asked.

Sunderland were the only Premier League side to pick up a point against the eventual champions last season in a thrilling 3-3 draw in March however they had an off day and were below-par. They were toothless in the final third partly due to the heavy reliance on the scoring prowess of the prolific Steven Fletcher so far such is the fact that he has scored all their goals so far. He had a quiet game yesterday which reflects their failure to get on the scoresheet. They have plenty of other goal sources in their team- now it is time for them to step upto the plate and ease the burden on the Scotsman.

Adam Johnson made his first return to the Etihad Stadium since the £10 million switch to his boyhood club in the transfer window- but failed to impress as David Silva, who restricted Johnson's playing time during his two year stay in Manchester, caught the eye. The England winger was included in Roy Hodgson's squad for the World Cup qualifiers with San Marino and Poland next week despite featuring in a handful of matches following his arrival as he recouperates fully from recent injury problems.

Fresh from winning the Premier League, his ambitious streak will want more success this campaign with the team he grew up watching and still supports today. His threat down the right was nullified while he rarely received the ball from colleagues although his best football is still to come. When withdrawn on 67 minutes for Saha, it was the former United striker entering the fray who was booed by home supporters as many City fans applauded the winger in recognising that his exit was merely out of sheer frustration of warming the City supporters. Mancini was first to openly admit in the post-match interview that the 24-year old made the right decision to leave in search of first-team football.

Plenty of factors are falling into place for City at the right time with the returns of Gareth Barry and Micah Richards after extended periods on the sidelines being welcome news and more options for Mancini as the fixtures pile up. The resurgent form of his four big-name strikers Dzeko, Balotelli, Tevez and Aguero will be something to ponder as they battle out for a regular place in the side. David Silva demonstrated signs of promise as the fatigue from the European Championships dissolves with some fanciful flicks, intricate play and neat threaded passes which is an ominous indicator for future opponents. The fact that these important players haven't hit the heavy heights of last seaon is perhaps the obvious explanation for the team's sluggish beginning this time around.

A player who deserves a special mention is Aleksandar Kolarov who orchestrated City's win and following two seasons filled with contrasting performances containing poor defending, the question marks surrounding his ability are slowly diminishing. Five minutes in, City fans got the start they were hoping for thanks to a setpiece which has vastly become his trademark. A curling, sumptuous free-kick from the Serbian which was measured to absolute perfection and caught Mignolet out.

His left-foot is one of the most deadly weapons of City's armoury. He was a constant threat all day down the flank, set up the second goal for Aguero and earlier chance for Balotelli, while he even had a part to play in the third by drawing the foul from Gardner for the free-kick by cleverly jinking back to deceive the full-back. Kolarov was definitively my man of the match. Now, instead of rotating the two left-backs simply to give them equal game time, Mancini has an even harder decision on his hands regarding whether to select Kolarov or Gael Clichy for the left-back berth. Adding goals to his game, in my book, gives Kolarov the edge however one aspect of his game that many people scrutinise an what needs addressing is his defending against top quality out-and-out wingers. If this improves, he has the potential to be one of the world's best.

In addition, the boss seems to prefer Clichy as a defender therefore Kolarov could be played as a left-winger which would then put pressure on the likes of Samir Nasri and Scott Sinclair to perform. Healthy competition is what City have in abundance all over the field which can only benefit the team but makes the manager's headache more severe.

Many would have looked at the City team sheet scratching their heads although many would have expected a reaction from the manager. Seven changes were made which paved the way for fringe and squad players to come in such as James Milner who thrived at the prospect of making a point and attracting the attention of his manager. Milner continues to earn the faith of the England manager but hasn't yet convinced his club gaffer. His display against Sunderland will have him knocking on the manager's door again. Yaya Toure captained the side and showed his leadership qualities on the pitch. His individual performance was far from his best although he cannot play well in every game.

City now have their first back-to-back league wins of the season however the upcoming international break could disrupt the momentum they have began to build. They have already dropped the same number of points this season as they did last season at home which will be a marginal concern however maintaining this phenomenal fortress record will be a priority for Manchester City. The fact they have been playing nowhere near their best and still churning out decent results and remain unbeaten epitomises the squad of players they have. He can replace quality with quality in all areas- not many Premier League bosses can do this. Perhaps not even Sir Alex Ferguson himself.

Second place in the table now is one step closer to where they would like to be- this result could be the turning point of their campaign and provide a platform for them to build on the start they have made. There is still a long way to go but City look to be heading back to the top of the tree. Manchester United and Chelsea may not be quaking in their boots just yet however watching the game, they will be ominously mindful that things are only going to get better for the reigning champions.