Surprise packages Napoli failed to take advantage when Milan drew 0-0 with Lazio in midweek when they lost at Chievo but red-hot striker Edinson Cavani helped make sure they did this time in a 2-0 home victory over lowly Cesena.
The Uruguayan, Serie A's top scorer with 18 goals, converted Christian Maggio's cross in the first half against second-bottom Cesena before Jose Sosa netted in stoppage time.
"We must improve our continuity," Cavani told Sky TV.
Milan's Alexandre Pato, preferred to Antonio Cassano upfront, latched on to Zlatan Ibrahimovic's pass to give the visitors a 29th-minute lead but Genoa forward Antonio Floro Flores struck home a loose ball just before the break.
Milan's midfield was almost back to full strength after injuries and suspension but the hosts defended stoutly and deserved their point, with Rossoneri fans now fretting that a first scudetto since 2004 does not look as clearcut as before.
"We knew it wouldn't be easy against Genoa," Milan coach Massimiliano Allegri said, adding that Cassano was still not fully fit after missing three months of action.
"We were unlucky with their equaliser and in the second half we didn't play well, we gave away too many balls.
"We know the championship is long. Napoli don't have any pressure, they are not obliged to win."
Tensions were high at the Marassi given the game was the first time since the death of a supporter 16 years ago in crowd trouble that Milan fans had been allowed to the encounter.
Scuffles between fans were reported but nothing major.
Third-placed Lazio missed the chance to pressure Milan themselves with a 1-1 home draw with Chievo.
Hernanes put the Romans in front with a ferocious freekick deep into first-half stoppage time but Cesar equalised.
Palermo lie just two points behind Lazio in fifth following a thrilling 4-2 win at struggling Lecce.
Previously struggling on-loan Juventus forward Amauri superbly netted his first Parma goal in a 1-1 draw with Fiorentina, who had Adrian Mutu back for the first time since being banished for quitting training last month.
Third-bottom Brescia won the relegation battle with basement side Bari, Alessandro Diamanti netting a penalty and Andrea Caracciolo an injury-time strike in a 2-0 victory which puts eight points between the two sides.
Bologna beat Catania 1-0 to send the Sicilians closer to the drop zone with new coach Diego Simeone failing to stop a slide.
Juventus ended their bad run with a 3-1 victory at Cagliari on Saturday when Alessandro Matri scored twice against his former club while Udinese continued their ascent with a 2-0 win over toothless Sampdoria.