They entered the debate hall like caged animals unleashed for a fight, and the audience in this arena of spin didn't have long to wait for the fireworks to begin: this was the debate of combat over substance, a bout rather than a forum.
The two political gladiators vying to be the next president clashed over both domestic and foreign policy, often speaking over each other and having to be restrained by the moderator.
At one point Romney told the President to wait until he had finished his point : "You'll get your chance in a moment. I'm still speaking", he said.
They first fought over the car industry in Detroit, then energy and then jobs. The two argued over their pensions, with Romney asking Obama if his investments included some in China.
Obama responded by hitting out at Romney's wealth, saying "I don"t look at my pension, its not as big as yours."
But perhaps the toughest exchange was over the attack on the US Embassy in Benghazi when a visibly angry Obama attacked Romney's claims that the administration had failed to declare the truth behind the incident : "I'm the one who has to greet those coffins when they come home, so you know I mean what I say."
Most instant polls show that those watching last night thought Obama came out on top, with 46 per cent of respondents to a CNN question saying that the President won, compared to 39 per cent for Romney.
Obama heads to the Mid-Western states of Iowa and this evening he'll be in Ohio. Iowa holds fond memories for the President: it's where he won the first of the primary votes in 2008 than propelled him to the presidency, while Ohio is a state that could provide a firewall against a resurgent Mitt Romney.
If the President can keep the Republican challenger at bay there, then his route to victory is much easier.
Mitt Romney will tread familiar turf this morning, holding a rally in Virginia, exactly as he did following his successful debate in Denver.
He'll be feeling less happy than back then, but neither of the men landed a knock out blow, and both will meet again in just six days time in Florida for what promises to be a thriller of a finale.