Surging Inter Milan, firmly back in contention for a sixth consecutive scudetto, can end AC Milan's season-long occupation of top-spot in Serie A when the city rivals clash on Saturday (1945 GMT).
Just two points now separate the sides with eight matches of the season to play following Inter's stunning run of results - 12 victories from 15 league games - since last season's Milan coach Leonardo took over the reins from Rafa Benitez at the start of the year when the gap between the sides was 13 points.
The volume level at the 80,000-capacity San Siro in what is one of the loudest, most colourful and hotly contested derbies in the game looks set to go through the roof when Leonardo, who spent more than a decade as a player, director and last season as coach for the Rossoneri, leads out the visiting Nerazzurri.
"I live my life based on love, not recrimination," the Brazilian, who had a fractious relationship with Milan owner and Italian prime minister Silvio Berlusconi, told reporters.
"Life goes on and you have to learn from every experience. Looking back on my career, I see only the good things and will never forget my 13 years at Milan."
While Jose Mourinho's Inter claimed the treble last season, the Brazilian, in his rookie year as coach, led Milan to third place before leaving through mutual agreement amid rumours of interference in team selection.
"The derby won't be crucial because after that there are another seven rounds," said the 41-year old, who has also guided Inter to the quarter-finals of the Champions League and semi-finals of the Italian Cup.
"What we wanted to do was get closer, get back in the race and challenge for the scudetto. We reach this derby in the best possible condition."
Inter's cause will be helped by the absence from the Rossoneri ranks of former striker Zlatan Ibrahimovic, who along with Inter defender Lucio, must watch the game from the sidelines because of suspension.
The big Swede, whose early penalty won this season's opening derby for Milan, has been out-of-sorts since the turn of the year with Milan winning just seven games as Leonardo's replacement in the hot seat, Massimiliano Allegri, has struggled to find an alternative.
"Ibra has done a lot for us so far this season but we are going to have to do without him," said Allegri. "I'm sure Milan will be up for it."
Robinho, likely to start in attack alongside compatriot Pato, has promised to dance the samba if he scores the winner.
"It's a key moment for us and we cannot afford to fail if we want to win the scudetto," the Brazilian told Milan Channel before addressing Leonardo's controversial decision to join the black-and-blue side of the city.
"It was his decision to go there but I can understand the Milan fans' disappointment. He will have to accept the consequences of his actions."
Without Ibrahimovic, Allegri is likely to add muscle to his attack in the shape of Kevin-Prince Boateng rather than Antonio Cassano.
For Inter, defenders Cristian Chivu and Andrea Ranocchia face late fitness test while last year's hot-shot Diego Milito, who has missed much of the season through injury, may recover in time for a place on the bench. One certain starter is Argentine midfielder Javier Zanetti, who will play his 35th consecutive derby and 39th in all.
Napoli, who host Lazio on Sunday (1130), are three points off the top while in-form Udinese, who visit Lecce on Sunday (1400), are a further three points back.