Mancini claimed this throughout the last campaign too - despite City going on to clinch the title on the final day of the season.

The City boss believes the striking partnership of Wayne Rooney and United's new-signing Robin Van Persie will make the team from Old Trafford even more formidable this season.

"I say this seriously," Mancini said ahead of City's Premier League opener at home to Southampton on Sunday.

"United play for the title every year for 20 years. We won the last championship but this can change in one year.

"For this reason I think they are favourites for the title.

"And now with (Robin) Van Persie - Van Persie is a really top player, he was the best striker last year. With (Wayne) Rooney, I think they will be the best couple of strikers in the Premier League.

"I think it (2012/13 season) will be harder than last year. This is normal. When you win everyone wants to beat you - we start with Southampton and this will be a difficult game.

Meanwhile, after being told by Mancini he may not be ready to make the first team, new signing Jack Rodwell insisted he will fight for a starting role.

The 21-year-old England midfielder completed a 12 million-pound move from Everton this week.

"I'm still young," Mancini said.

"I believe in my ability but there's great players here. I want to learn. I want to improve. And that's why I'm here for the challenge.

"Everton are a great team with great players as well. But I see it as a step up here. It's a great challenge and I'm sure I will improve my game."