Aguero's stunning entrance leaves Mancini wanting more

'He's not yet 100 per cent,' says City manager after £38m striker scores twice as new boys Swansea are overwhelmed 4-0

Sergio Aguero came off the bench to make his debut before scoring twice (GETTY IMAGES)

Manchester City's record £38m new signing Sergio Aguero signalled his arrival and his club's ambition last night by coming off the bench to deliver two goals and create another in a 4-0 defeat of Swansea City, despite his manager Roberto Mancini later declaring he is not even yet match fit.

Aguero, the first player in six years to score twice on his Premier League debut, formed an immediate partnership with David Silva in his 31 minutes on the pitch which produced what Mancini described as the "perfect" start to the Premier League campaign. "I know Aguero very well but I don't think he is 100 per cent because he worked only one week with the team," said Mancini, who suggested that there was no development in the £22m negotiations with Arsenal for midfielder Samir Nasri. "Maybe he needs to improve but it is his debut so it is good that he scores. He scored a lot of goals in Spain and Argentina I think he is a fantastic striker but he plays with us [for] only 10 days."

The 23-year-old striker was a strategic signing which City made because of uncertainties surrounding the future of both Carlos Tevez – who was not seen here last night – and Mario Balotelli, who was dropped. Mancini reiterated that Tevez could remain at City. "I don't know [if he was in the stadium] but this morning he worked at Carrington and for the next game he will be available."

City's delay in concluding the Nasri deal may be in part in out of courtesy to Arsenal, who lost Cesc Fabregas late on Sunday evening and the Frenchman's arrival on a five-year deal worth £165,000 a week is still expected imminently.

The City goalkeeper Joe Hart said Aguero's contribution last night had been an education for him. "He's decent isn't he?" Hart said of the signing from Atletico Madrid. "He's come in at £38m which is a big price tag but it looks like £38m well spent. I've not seen that much of him because the manager has kept him quite well protected because he's had a big summer." Edin Dzeko also looked sharper than last season, strengthening City's optimism as they make the immediate running, joint top of the season's first table. "I'm happy for him as well because this will be an important year for him," Mancini said of the Bosnian striker.

The Swansea manager, Brendan Rodgers, justifiably reflected that his newly-promoted side, who will need to defend more strongly to avoid the fate of Blackpool and Burnley as pure footballing sides in the top flight, had reasons to leave Manchester with hope after beginning their first season in the top flight in 28 years.

"It can go one of two ways you can be daunted by the task or play your way," Rodgers said. "It was harsh on our team. For the first hour the players showed great confidence and great quality with the ball and looked like they could be a threat

"We could have defended better for the first three goals and the fourth goal was a great goal from a world-class player. I know we will improve. Overall I was very happy that the players could come and have that confidence with the ball." Rodgers insist he would not forego his side's passing game in the name of survival. "We like to keep the ball," he said. "Our idea is to control the game with that cutting edge. [What you've seen] is the way we play and I'm confident we can do very well at his level."