Brazilian midfielder Hernanes went from hero to villain as 10-man Lazio let slip a potential win in a thrilling derby against Roma that was marred beforehand by clashes between fans and police.
The 'Derby della Capitale' was much anticipated but the tension got too much for some prior to the encounter at the Olympic Stadium as two Roma supporters were stabbed in clashes.
The incidents prompted Rome's mayor to call for calm, yet on the pitch it was anything but as Hernanes gave Lazio a 16th minute lead in spectacular fashion, only to miss from the penalty spot early in the second half.
Roma were awarded a penalty just before the hour and Francesco Totti stepped up to beat Federico Marchetti but despite the 69th minute expulsion of Lazio defender Giuseppe Bavia the hosts failed to capitalise.
Roma's sixth draw of the campaign left the Giallorossi in seventh place in Serie A, 23 points behind leaders Juventus and three behind Lazio.
Coach Aurelio Andreazzoli admitted Roma were happy to see Hernanes' penalty blunder.
"I was anxious at the penalty because 2-0 would have made things difficult," he said.
"But it was a great match and I'm just sorry I couldn't give our fans the three points."
Lazio coach Vladimir Petkovic, meanwhile, refused to blame Hernanes.
"The missed penalty changed things for us but I would prefer to see the glass half full than half empty," said the Bosnian,
Roma, looking for the win that would boost their chances of a place in Europe next season, started brightly with Totti crossing for Erik Lamela at the far post only for the midfielder to see his header go straight to Marchetti.
The hosts pressed on in their search for an early goal but the first signs of Lazio's threat came on 13 minutes when Antonio Candreva stung the hands of Roma 'keeper Maarten Stekelenburg with a superb angled drive.
Barely a minute later Lamela pounced on some slack defending at the Lazio byline, doing well to keep possession before seeing his attempt to set up a colleague fall at the feet of a Lazio defender.
Three minutes later the Biancocelesti took the lead in stunning fashion when Hernanes struck what will likely go down as one of the goals of the season.
After collecting a cross from the left the Brazilian midfielder took two touches, turned on to his left foot and sent a superbly-struck shot past the hands of Stekelenburg from 25 metres out.
Only a minute later Hernanes threatened again but after dribbling his way through Roma traffic in the area he saw his effort bundled to safety.
Lazio looked dangerous at every turn in the first half but Roma survived the onslaught and emerged with more purpose after the half-time interval.
Their enthusiasm waned, however, after just three minutes when a handball from defender Marquinhos gave the visitors a penalty.
After his first-half wonder-strike, Hernanes, however, contrived to send the ball high and wide of Stekelenburg's goal.
The referee then pointed to the penalty spot after the Brazilian fouled Miralem Pjanic on the edge of the area minutes later, with Totti stepping up to squeeze his shot past Marchetti to pull Roma level.
The goal buoyed Roma and the hosts came close when Lamela's shot was pushed wide, then Alessandro Florenzi spurned the chance to beat Marchetti when latched onto the rebound from a Totti freekick.
Roma were given a further boost when Biava saw red for a second bookable offence on 69 minutes.
However they failed to capitalise and victory seemed destined to escape them after Lamela missed a gilt-edged chance when he headed Totti's cross over from a metre out in the latter stages.