In a major blow to Roberto Mancini and Manchester City, Daniele De Rossi has declared that he intends to remain a Roma player for the foreseeable future.

Regarded as a complete midfielder, the 29-year-old Italy international has been prominent on the City manager's shopping list for some months but on Tuesday De Rossi ruled out the prospect of relocating to the Etihad Stadium.

He said in Rome that despite contact between the clubs over a proposed £31m transfer which would have reportedly earned him £130,000 a week, there was no chance of him leaving for north-west England. "I'm staying for this team, for the affection of the fans, because I am a Roman and because I believe in this project. I'm happy here. I feel good here. I haven't asked anyone to leave. What I promise is that the day I want to leave Roma to win the Champions League or to earn more money, I'll say so publicly."

Although Zdenek Zeman, Roma's new coach, confirmed that discussions had taken place with City over De Rossi the Czech, too, stressed that the midfielder would be staying at the Stadio Olimpico. De Rossi, meanwhile, dismissed suggestions that he had fallen out with Zeman.

"Has Mancini ever called me about Daniele?" said Zeman. "Yes, several times. The last time I heard from him was three weeks ago."

At least the news for City is proving brighter regarding Sergio Agüero – whose sole addition to his Premier League title-winning squad so far this summer has been the acquisition of the midfielder Jack Rodwell from Everton.

Agüero twisted his right knee early on in Sunday's 3-2 win over Southampton and it was initially feared that a fair tackle from Nathaniel Clyne had left the Argentina striker with severe ligament damage and the prospect of around six months out of action.

Although City are still waiting for the results of MRI scans on the knee, all the indications are that the problem is appreciably less serious than first feared and Agüero will be unavailable for weeks – possibly three or four – rather than months. Mancini is scheduled to reveal the diagnosis and prognosis during his weekly press conference on Friday.

Mancini had said he would seek attacking reinforcements were the injury to prove serious, but all the available evidence suggests otherwise and City possess the resources to cope with Agüero's absence for up to a month. "Usually the knee is always dangerous," said Mancini. "So this injury was maybe strange."

It now seems unlikely that City's manager will make a long-predicted move for Fiorentina's young Montenegrin striker Stevan Jovetic. The 22-year-old may have found himself on a plane to Manchester had Agüero faced ligament reconstruction surgery.

However, Scott Sinclair appears to be closing in on a reported £5m move to City, with Swansea's first-team coach, Alan Curtis, saying: "He's not really interested in signing a new contract and I think Man City have made a bid. So it's just a matter of time now before it happens and it's good for both parties."