Inter Milan lead Serie A heading into the Christmas break, but a 2-1 defeat to Lazio means their advantage is slight.
Roberto Mancini's men -- one point clear at the top -- might have opened a four-point gap on Scudetto rivals Fiorentina and Napoli had they beaten struggling Lazio at San Siro on Sunday night.
But Antonio Candreva opened the scoring to ensure Inter would fight an uphill battle and Mauro Icardi's second-half leveller was rendered redundant when Candreva stuck away his own saved penalty with three minutes remaining.
Felipe Melo conceded that spot-kick and later saw red for a moment of madness, with Lazio midfielder Sergej Milinkovic-Savic following him down the tunnel in stoppage time.
Troubled Lazio can head into the festive period with cause to be cheerful, having claimed a first league win in eight attempts, while Inter can begin to look at the transfer window and consider how they might strengthen their title bid.
Samir Handanovic endured a busy night in the Inter goal and he was given food for thought after only two minutes as Miranda's poor backpass left him exposed to Alessandro Matri.
He dealt with the threat and span the ball upfield for his team-mates to launch a raid that ended with Stevan Jovetic and Ivan Perisic combining to test Etrit Berisha, who rushed off his line to close the door on the Inter pair.
It was Lazio who opened the scoring in the fifth minute. The game's first corner found its way to Candreva and the Italy midfielder unleashed a first-time shot that fizzed between Handanovic and his near post.
Despite the early promise the half was largely disrupted by mistakes and needless fouls, with the free-kicks that resulted going largely to waste. Alex Telles did, however, find the target with his attempt from 30 metres out.
Lazio came close to doubling their lead one minute before the break as Candreva spooned over the crossbar from a one-on-one with Handanovic, having been set up cleverly by Felipe Anderson.
With nothing falling for Inter following the restart, Mancini shuffled his pack, introducing Adem Ljajic and Marcelo Brozovic for Jovetic and Jonathan Biabiany just before the hour.
The tactical change drew Lazio out of their established trenches and Inter struck. Perisic, who started the game on the right wing, cut inside from his new position on the left to pick out Icardi for a cool finish beyond Berisha.
Perisic almost turned goalscorer when heading just wide at a 73rd-minute corner and only a brave block from Abdoulay Konko stopped the Croatian from repeating the trick moments later.
In the 85th minute Lazio were gifted an opportunity to win the game and condemn Inter to a rare home defeat.
Melo fouled Milinkovic-Savic when there was no real danger and Candreva stepped up to take the penalty. Handanovic denied the former Udinese man but could not keep him from converting the spilled shot.
The evening then took a turn for the worse for Inter, and Melo, when the Brazilian chose to kick Lucas Biglia in the face.
A straight red card followed and Milinkovic-Savic was not far behind in earning his marching orders, the Serbian collecting a second yellow for kicking the ball away.