Resurgent Ronaldinho netted a hat-trick to help AC Milan hammer 10-man Siena 4-0 at San Siro on Sunday and close the gap on Serie A leaders Inter Milan to six points.
The title race is now very much on given Inter only drew 2-2 at Bari on Saturday, Milan have a game in hand and the top two meet in the city derby next weekend.
Juventus are out of the running though after a 1-0 defeat at Chievo, their fifth loss in seven games in all competitions. Gennaro Sardo netted for the dominant hosts in the first half but under pressure Juve coach Ciro Ferrara can blame his terrible injury problems, which meant Michele Paolucci started upfront having been recalled from Siena only on Saturday.
Claudio Ranieri's AS Roma have gone above former club Juve into third, 11 behind Inter, after on-loan striker Luca Toni grabbed his first two goals for the club from close range in a 3-0 home win over Genoa.
Napoli are level with Juve and can move third with victory at home to in-form Palermo later.
Milan had a poor start to the season under new coach Leonardo but their remarkable renaissance has largely been thanks to Ronaldinho and Marco Borriello, who like Toni could now make a late bid to gatecrash Italy's World Cup squad.
Striker Borriello won a 12th-minute penalty when he was brought down by keeper Gianluca Curci, who was given a straight red card, and Ronaldinho confidently slotted in the spotkick.
Borriello, whose career was held up by a 2007 drugs ban, then volleyed in Andrea Pirlo's cross with his wrong foot to prompt a standing ovation at the San Siro.
Ronaldinho, reborn after recapturing some of the form which made him 2004 and 2005 world player of the year, then nodded in David Beckham's second-half corner and fired in a superb shot which rekindled memories of his glory days at Barcelona.
Siena, unlucky to lose 4-3 against Inter last weekend, slipped four adrift at the bottom after relegation rivals Catania drew 1-1 at Sampdoria and Atalanta stunned Lazio 3-0 at home in Bortolo Mutti's first game in charge.