AC Milan haven't lost in Serie A since December's shock hammering at the hands of Roma and go into their tie with Napoli in good form, even if their last game against Fiorentina was not their finest performance.
Napoli, meanwhile, have been somewhat lukewarm of late and though they currently lead the Rossoneri by four points in the battle for second, they know that they must perform in Milan and kick-start a late-season surge.
This tie is certainly the most important of the round on the peninsula this weekend, and with two teams known for their attractive, attacking style it's definitely an exciting prospect for calcio fans everywhere. So what are the key battles to look out for at the San Siro?
Milan's 4-3-3 against Napoli's 3-4-1-2 is going to be an interesting tactical battle. Both sides play attractive football in formations that are both positive and quite dynamic.
Both Walter Mazzarri and Massimiliano Allegri, then, will have their work cut out for them as they try to maximise their own effectiveness while figuring out a way to exploit weakness in their opponent's shape.
Allegri and Mazzarri have also both been the subject of intense media speculation in the last few months, and it seems likely that one of them at least will move clubs in the summer. Napoli and Milan have had mixed seasons so far, but the coaches will be mindful that overcoming those slumps and guiding their team to second place will give them more bargaining power come the summer.
It was the first leg of this fixture that actually sparked Milan's revival this season, thanks in no small part to Stephan El Shaarawy.
The young Italian earned deserved praise for an excellent individual performance against Napoli, when his brace allowed Milan to share the spoils at the San Paolo despite having gone down to early goals from Gokhan Inler and Lorenzo Insigne.
This time around, he'll be a marked man. No matter where he finds himself on the pitch, El Shaarawy should expect to be under close scrutiny. The memory of his two goals earlier in Naples—in particular his stunning first—will still linger in the minds of Walter Mazzarri's men and they'll all be working hard to ensure he doesn't find it so easy to score this time around.
Christian Abbiati was awful against Napoli at the San Paolo. Both of the Partenopei's goals should have been saved and were it not for El Shaarawy's efforts up front, the veteran keeper would have felt very foolish indeed.
He's by no means the worst keeper in the league, but the 35-year-old's abilities do divide opinion and there are many who feel that he's one of the few remaining weak links in what is otherwise a youthful squad, full of promise.
Abbiati is also out of contract in the summer and there's a certain amount of uncertainty surrounding his future. Lazio's Federico Marchetti has been mentioned as a possible replacement by former Milan midfielder Giovanni Lodetti, but a fine performance against Napoli—and their most dangerous front man, Cavani—would do Abbiati's standing the world of good at what is a crucial time in his career.
Giampaolo Pazzini might not make headlines like Mario Balotelli, but he has no problem creating goals.
The former Sampdoria man is a different player to Super Mario, and though less naturally gifted than Balo, he adds an extra dimension to Milan's all-round game.
Pazzini's eye for goal and his work-rate are obvious strengths, but the Italy international is also excellent at holding up play—something that could be crucial in giving El Shaarawy time to find space in dangerous positions high up the pitch.
Speaking after last week's win against Genoa, Paolo Cannavaro was quick to remind everyone that Napoli are about more than just attacking talent.
“Beyond the victory, which allows us to extend our lead over Milan," said the Naples-born defender, "it was also important not to concede a goal. Many forget that we are the best defence in the league, so congratulations to us.”
Cannavaro and Co. will have be at their very best to stop Pazzini.
While Cannavaro watches Pazzini, Milan will want to keep a close eye on Napoli's Macedonian-born Swiss midfielder Blerim Dzemaili.
The 27-year-old is on blistering form, and though in two years in Naples he had only scored three times in the league, Dzemaili has now found the net four times in his last two games.
With Marek Hamsik, Goran Pandev and Cavani leading the line Milan's defence will be busy on Sunday, but their midfield will need to stop the tricky Dzemaili further up the pitch unless they want to become his latest victims.