Juventus won the battle of the two challengers to Inter Milan's current domination of Italian football with a convincing win over AC Milan.
Alessandro Del Piero opened the scoring with a penalty in the 15th minute before Pato equalized after half an hour.
Giorgio Chiellini restored the hosts' advantage within minutes and Amauri ensured their domination was reflected by the 3-1 scoreline at half-time.
Massimo Ambrosini gave Milan some unexpected hope in the 56th minute, but that was dashed when former Juve defender Gianluca Zambrotta was sent off 10 minutes later and Amauri added his second and Juve's fourth 20 minutes from time.
The win lifts Juve to within six points of Inter, leaving Milan and Napoli three points in their wake.
This was a game that not only lived up to, but exceeded, its pre-match billing as the two sides who have dominated the championship for almost two decades delivered the goods on a cold and wet night at the Stadio Olimpico.
Juve set out their stall immediately with Amauri trying an acrobatic overhead kick from 15 yards in the 10th minute.
Olof Mellberg then headed just wide of the post before Del Piero put the Bianconeri ahead from the spot in the 15th minute.
The Italy forward earned the penalty himself when he was fouled unnecessarily by Marek Jankulovski just inside the area and he placed his spot-kick just beyond Christian Abbiati's reach.
Milan reacted well and Ambrosini should have equalized in the 18th minute, missing a golden opportunity with a free header from only five yards out after beating the offside trap to meet Clarence Seedorf's cross.
However, they were back on level terms in the 31st minute when Kakha Kaladze set Ronaldinho loose on the left and his cross allowed Pato to tap into an open goal from six yards.
The Rossoneri were level for only three minutes before Chiellini powerfully headed the home side ahead for the second time from a corner.
Amauri's ninth goal of the season in the 41st minute, a typical striker's header down into the ground, gave Juve a two-goal cushion at the break, a lead they thoroughly deserved.
Juve continued where they left off in the second half with Mohamed Sissoko testing Abbiati from 20 yards.
But they were made to sweat in the 56th minute when Ambrosini's shot took a wicked deflection off Chiellini to leave Alex Manninger wrong-footed and bring the Rossoneri back to within a goal of their hosts.
However, they never looked likely to equalise, and their hopes grew even slimmer when they lost Zambrotta to a red card after he hauled Paolo De Ceglie down just outside the area to earn a second caution.
Juve were then denied a clear penalty when a handball by Seedorf went unnoticed.
The hosts did extend their lead soon after, however, with Amauri grabbing his 10th of the season after playing a fine one-two with Sissoko and beating Abbiati at his near post.
Del Piero then hit the post as the home side threatened to run riot.
But Claudio Ranieri's side almost appeared to take pity on their opponents and settled for what was already an emphatic win.
Although the defeat may not end Milan's hopes of winning the Scudetto, they now trail their city rivals Inter by nine points while Juve give chase in what looks set to develop into a two-horse race for the title.
