Relegation-threatened Genoa were losing 4-0 early in the second half when home fans began throwing flares and smoke-bombs on to the field, causing the referee to halt the game.

Some also climbed over the perspex barrier around the pitch and demanded that the players take their shirts off, the logic being that they were not worthy of wearing them.

Several players did so and the game re-started with Siena, who had retreated to the dressing room, eventually winning 4-1.

Ibrahimovic's 24th Serie A goal of the season, which canceled out Gaston Ramirez's first-half effort, was not enough to prevent Milan dropping two home points in the title race with Juventus, who were at home to AS Roma later on Sunday (1845).

Champions Milan have 68 points from 33 games, level with Juventus who are still unbeaten.

Third-placed Lazio, who have 55 points, dropped two home points when they conceded an injury-time equalizer in a 1-1 draw with relegation-threatened Lecce.

Brazilian midfielder Matuzalem gave Lazio the lead in the 82nd minute when he was allowed a free header at the far post.

Valeri Bojinov grabbed a deserved equalizer for Lecce in stoppage time, firing home from 12 meters after a series of ricochets in the area.

Lecce, who are 18th with 35 points and occupy the third relegation spot, moved within a point of Genoa.

Fiorentina's relegation worries persisted as they missed a penalty in a 0-0 draw at home to Inter Milan, who are unbeaten since the departure of coach Claudio Ranieri last month.

Inter goalkeeer Julio Cesar gave away the penalty with a foul on Andrea Lazzari and escaped with a yellow card as Fiorentina demanded he be sent off.

The Brazilian then atoned by saving Adem Ljajic's effort from the spot in the 69th minute.

Fiorentina are 15th with 38 points, three clear of Lecce.

Inter, seventh with 49 points and three games to play, have won two and drawn two of their four games under caretaker coach Andrea Stramaccioni who became Inter's fifth coach in the last two seasons Bologna took the lead at the San Siro when Mark van Bommel gave the ball away to Alessandro Diamanti on the halfway line and he burst forward and laid the ball off for Gaston Ramirez, who coolly slotted the ball into the corner in the 26th minute.

Milan were struggling but the game changed in the last half hour as Bologna lost composure in midfield while the introduction of Urby Emanuelson for the hosts in the 70th minute brought them to life.

Ibrahimovic nearly equalized with an overhead kick in the 87th minute but three minutes later, Gabriel Mundingayi lost possession in midfield, a long cross from Emanuelson found the Swede at the far post and he scored with a first-time shot.

Milan nearly claimed a late winner as Antonio Nocerino sent a shot flashing past the post and Robinho headed wide following another Emanuelson cross from the left.