AC Milan handed Juventus the advantage in the Serie A title race as they lost 2-0 at Lazio on Wednesday, with Inter Milan held to a draw in an eight-goal thriller against Palermo.
Milan trail Juve by a point at the top but the Old Lady of Turin have a game in hand after their match at Parma on Tuesday night was called off due to snow.
Third-placed Udinese closed the gap to the leaders to three points with a 2-1 win at home to Lecce while fourth-placed Lazio are now just two points behind that.
Milan coach Massimiliano Allegri denied his side have made their title rivals' life easy.
"We played badly but there's still a long way to go, the road is not clear for Juve," he said. "But I'm sure that this defeat will do us good. Even in recent games when we won we didn't always play well so this will serve us well."
Lazio coach Edy Reja was delighted with his team, who were missing several forwards.
"We had to keep things tight because Milan are good at breaking from deep," he said. "We played well and gave away few chances. I've very satisfied with the lads who showed great determination in an emergency."
Italian Serie A results on Wednesday:
Cagliari 4 (Thiago Ribeiro 6, 48, Pinilla 41, Ekdal 90) Roma 2 (Juan 13, Borini 34)
Inter Milan 4 (Milito 22, 55-pen, 61, 69) Palermo 4 (Mantovani 17, Miccoli 52, 66, 85)
Lazio 2 (Hernanes 76, Rocchi 85) AC Milan 0
Udinese 2 (Paziena 2, Di Natale 36) Lecce 1 (Di Michele 26)
Napoli 0 Cesena 0
Atalanta vs. Genoa; Bologna vs. Fiorentina; Siena vs. Catania