Considering the earlier stance of Tevez never being welcome at City again and will never play for the first team and Mancini's turn around here, its VERY clear which side is requesting help from who.
City have been cack for 2 months, they've thrown away a HUGE lead and let a pretty average Utd get right back in the fight and Spurs aren't out of the equation yet, all with one "meh" performance after another.
They can't resort to one up top with Yaya/Silva/Nasri in support because, all three of those players have been the most disappointing and in the worst form in the past 2 months. Yaya looked decidedly tired and unimposing again last night and in crucial game, got taken off due to being so ineffective and tired looking.
He looked tired before xmas, played poorly for a month then went to the ACN, expecting him to come back in top form and not looking even more tired was always a little daft.
What was completely expected was, when the chips were down, Milner and Barry aren't even close to good enough to carry the team, Silva has never been picked up by a "top" team before because he's inconsistent and doesn't fight in tough games, and same for Nasri in his whole time at Arsenal. Messi is in bad form, but he runs and closes down as much as anyone else in the team while Silva aimlessly jogs around doing not much of anything.
They can still win it, but someone with a bit more fight, experience, consistency would help them quite a lot.