A change of coach, injuries and a possible lack of hunger after last term's treble mean Inter's bid for a sixth straight scudetto is floundering with the side down in seventh, 13 points behind leaders Milan with two games in hand.
Inter coach Rafael Benitez departed on Thursday after a torrid time since replacing Jose Mourinho in June.
"He need times to develop his role, his way of playing. I think removing him is mistaken," ex top-flight coach Renzo Ulivieri, head of Italy's managers' association, told Reuters.
Moaning about a lack of signings after Inter's Club World Cup win last Saturday has also contributed to Benitez's demise and the side do need new recruits in January if they are not going to relinquish their title without a fight.
Leonardo, Milan coach last term in his first job in management, is being tipped by the media to take over at rivals Inter in a move which would seem incredible in other leagues but is nothing new in the wacky world of Italian football.
Milan and their fans can have no complaints about their old coach switching allegiances given their success this term has been built on the signing of ex-Inter forward Ibrahimovic, whose skill and power have added a new dimension to their attack.
The Swede, seeking his own seventh consecutive league crown, was a major factor in Inter winning the 2007, 2008 and 2009 scudettos and after one mixed title-winning season at Barcelona he is back wowing Serie A but in red and black stripes.
Another reason for Milan leading by three points just before the halfway stage of the season is coach Massimiliano Allegri.
JUVENTUS LURKING
Almost a novice at this level having only ever managed Cagliari in the top flight, Allegri is a shrewd operator and his decision to drop the fading Ronaldinho to the bench has allowed Milan to develop a more urgent and direct style of play.
The lethargic Brazilian could head home in the January transfer window given Milan are bringing in Sampdoria's combustible but skilful forward Antonio Cassano while the return to fitness of striker Alexandre Pato also boosts options.
However, Milan are guaranteed nothing yet and defeats to Cesena, Juventus and AS Roma suggest the fragility shown under Leonardo when they finished third last term still lingers.
Rather than watching Inter run away with the scudetto, this title battle is enthralling because of the new teams involved.
Lazio, whose last title was in 2000, were relegation candidates last term but coach Edy Reja has guided the Rome club to joint-second to everyone's surprise thanks also to the cut-price purchase of superb ex-Sao Paulo midfielder Hernanes.
"Calmness, the right balance, a united dression room and a coach who has an incredible rapport with his team. Reja is the key," Lazio owner Claudio Lotito told reporters.
Napoli are level with Lazio after a series of stoppage-time winning goals which have led media to coin the phrase "Mazzarri time" in homage to mul
