A shot from AC Milan's Zlatan Ibrahimovic hit both posts but that was the closest either side came to scoring in a 0-0 draw between the Serie A leader and third-place Lazio on Tuesday.
Milan stretched its lead to five points ahead of Napoli, which visits Chievo on Wednesday. Lazio is seven points behind.
Milan dominated throughout and in the 51st minute Ibrahimovic's shot from just beyond the area ricocheted first off the left post, and then the right before bouncing away as the Sweden striker looked on incredulously.
"We had a lot of chances right up until the end. Lazio defended well but I don't think they ever shot on goal tonight," Milan coach Massimiliano Allegri said. "We played a good game and did some good things and I think we deserved to win. But that's football and we've got to accept it."
Already without 12 players due to injury and suspension, Milan took a further battering in central defense. Daniele Bonera exited following a first-half collision and his substitute Nicola Legrottaglie, who transferred from Juventus on Monday, had his forehead bloodied in a collision and was carried off on a stretcher in the 85th.
Both players were taken to the hospital, with Allegri saying Bonera has suspected head trauma and Legrottaglie suspected cervical trauma.
Ibrahimovic also had a chance in the 28th, but his header deflected wide off a defender. Newly-signed Dutch international Urby Emanuelson then set up Mathieu Flamini with a perfect cross but the Frenchman wasn't able to take advantage.
Ibrahimovic missed another attempt wide in the 53rd and Robinho had a shot cleared off the line by defender Giuseppe Biava in the 70th.
Crafty forward Antonio Cassano came on for Alexandre Pato in the 70th but didn't create much despite Lazio sitting back, apparently content with the draw.
In other matches Wednesday, Juventus visits Palermo and AS Roma hosts Brescia, while Inter Milan faces Bari on Thursday.