Thousands of Iraqis, including members of the security forces, defied a strict government ceasefire order to welcome their football squad's Asian Cup victory on Sunday with a barrage of gunfire.
Baghdad security authorities had imposed an overnight vehicle curfew in order to prevent insurgent car bomb attacks and ordered police to arrest anyone who took part in the traditional celebratory gunfire.
Al Jazeera's Hoda Abdel-Hamid was in the northern Iraqi Kurdish region in Irbil, said: "The scenes are incredible. I have been in Iraq for more than 11 years, and I have never seen anything like this.
"Traffic is everywhere. It's extremely meaningful here. I spoke to a young boy this morning who said "if only our prime minister would learn from the team."
Mahmoud's goal came after concerted Iraqi pressure when Hawar's corner directed at the far post went beyond goalkeeper Yaser Al Mosailem and onto the striker's head for a terrific header.
Iraq, who have captivated the football world with their inspirational progress at the tournament, finished conceding just two goals in their six games and put a spanner in the free-flowing Saudis, who were the leading scorers with 12 goals.
It was a triumph for Iraq's Brazilian coach, Jorvan Vieira, 54, who only signed a two-month contract with the Iraqi Football Federation and said Saturday he intended to quit the job after accomplishing what he had set out to achieve.
Australian referee Mark Shield issued five yellow cards - three to Iraq and two to the Saudis - as tackles flew in during the furiously paced match.
The Iraqi defence handled the twin Saudi threat of Malek Maaz and Yasser Al Qahtani capably with left-back Bassim Abbas having a particularly solid game with his trademark acrobatic overhead clearances.
There was plenty of off-the-ball incidents with defender Ali Hussein Rehema going down clutching his face in the penalty area awaiting a free kick with the referee speaking to Al Qahtani but not taking the matter further.
Iraq, who had the better chances in the fiercely-contested exchanges, went close in the 28th minute when Karrar Jassim wriggled past two defenders and forced goalkeeper Yaser Al Mosailem to punch clear.
Al Qahtani had his only chance of the half when he made some space nearing half-time but blazed his shot well over the bar.
Iraq goalkeeper Noor Sabri made a flying save to prevent a screaming volley from Taiseer Al Jassam going in and the action switched to the other end where Al Mosailem made a double save to stop Mahmoud and then Hawar Mohammed from scoring.