AC Milan slipped up for the third time in four matches to hand the Serie A title initiative to Juventus following a 1-1 draw at home to Bologna on Sunday.
On a dramatic day, Genoa's clash at home to Siena was held up for half an hour as fans protested the hosts' performance -- they were 4-0 down at the time -- by throwing flares onto the pitch and climbing safety barriers.
At the San Siro Gaston Ramirez gave Bologna a first half lead and Daniele Bonera was sent off for the hosts 10 minutes from time before Zlatan Ibrahimovic rescued a point.
But the result leaves Milan level on points with Juve, who host Roma later on Sunday, but with a worse head-to-head record.
Milan have only picked up five points from their last four league games and have only one win in six in all comeptitions.
And they displayed a remarkable lack of urgency in the first half for a team fighting to retain the Serie A crown.
Milan created little to get excited about in the first period, although Ibrahimovic had a glorious chance to open the scoring when teed up by a clever pass from Clarence Seedorf, only to fail to hit the target.
The hosts were made to pay on 26 minutes when indecision from Mark van Bommel saw Alessandro Diamanti break form the halfway line and slip in Ramirez to finish low into the corner.
Antonio Nocerino was crowded out trying to get on the end of a Robinho cross while at the other end Gaby Mudingaye broke free but shot past the far post for the visitors.
Milan piled on the pressure after the break and Ibrahimovic seemed to have the ball in the net but was pulled back for a controversial offside.
Robinho forced goalkeeper Federico Agliardi to tip his shot over the bar.
Milan's task grew complicated 10 minutes from time when Bonera went through the back of Robert Acquafresca and picked up a second booking, leaving the champions to finish the game with 10 men.
Ibrahimovic tried a spectacular overhead bicycle kick but failed to hit the target.
But the big Swede found the net a minute from time, tapping home a deep cross at the back post.
Lazio squandered the chance to exploit Udinese's 0-0 draw at Chievo on Saturday night as an injury time strike by Valeri Bojinov earned Lecce a 1-1 draw in the capital.
A group of home fans disgraced themselves with anti-semitic chants during the first half to make matters worse.
Lazio looked to have snatched the win eight minutes from time when Brazilian Matuzalem struck but Lecce had the last word.
The third-placed Romans are now three points ahead of Udinese and four ahead of Napoli, who beat Novara 2-0 on Saturday, with five games to play in the race for Champions League football next season.
Inter Milan's own Champions League qualification hopes slipped further away following a 0-0 draw at Fiorentina.
Sixth-placed Inter still trail Lazio by six points and it could have been worse as Fiorentina missed a penalty in a lacklustre affair.
The only real plus for Inter was that coach Andrea Stramaccioni maintained his unbeaten start on the bench.
But the 36-year-old still hasn't given up on third place.
"We're not hiding, that's our aim and we'll keep believing as long as it's possible," he said.
"We're in our first few matches, we need time to learn but I was pleased with our shape, even though we didn't develop our game as we wanted.
"We want to build down the flanks but we only managed that in part."
Julio Cesar gave away the penalty midway through the second half by bringing down Andrea Lazzari but made amends by saving Adem Ljajic's spot-kick.